Prospectus Hit and Run: NL Rotation Rumble

Last week, I had the pleasure of participating in the Baseball Prospectus annual stop at Washington DC's Politics and Prose bookstore. As I joined Steven Goldman, Derek Carty, and Adam Sobsey in the question-and-answer session with the 125 or so attendees—yet another packed house that lived up to our past history there, for which we profusely thank our DC-area readership and the store—the most apparent difference from years past was the bona fide sense of hope the audience had about the Nationals.

Last year's squad finished at 80-81, its best record since their 2005 inaugural in the nation's capital, and not only are they poised to add Bryce Harper at some point this season, but with full campaigns from Stephen Strasburg, Jordan Zimmerman, Gio Gonzalez, and Edwin Jackson—a quartet who combined for just 185 1/3 innings for the team last year—replacing the likes of Livan Hernandez and Jason Marquis—they've significantly improved in a critical area. Their 81-81 PECOTA forecast is just six games behind the division favorites, the Phillies, and four games worse than the Braves, Marlins, and Cardinals, the leading wild card contenders. In a year in which the playoffs have expanded to accommodate another team, the Nationals' hope is legitimate.

How well does their revamped rotation stack up against the rest of the league? As with last year, I dug into our Depth Chart-based PECOTA projections to examine each team's selection of starters, with an eye toward something between fun argument starter, instructive inquiry into the forecast system's inner workings, and premature playoff preview. I tallied the best Terrific Tandems, Big Threes, Front Fours, Fab Fives, and Six-Packs for each NL team. (I'll repeat this exercise for the AL next time around.) I took each team’s top six starters into consideration, since depth is important, and in many cases an alternate with fewer innings—a swingman, midseason callup, or late-healing frontliner—forecasts to be more valuable than a pitcher with a higher innings total.

Before turning to those questions, though, it's worth asking which NL team did the most to revamp their rotations using trades and free-agent signings. Last year the honor went to the Brewers, whose additions of Zack Greinke and Shaun Marcum—forecast for a combined 6.6 WARP, they turned in a total of 6.2—propelled Milwaukee to its first NL Central crown and just its second post-season appearance since 1982. Here's how the additions stack up this year:

The Reds have done the most to boost their rotation from outside, trading a quartet of players (including Volquez) for the 24-year-old righty Latos. The Pirates rank a surprising second, even given the injury-related innings adjustments to Bedard (forecast for 126 innings based upon his history) and Burnett (122 innings thanks to a two-month absence due to orbital surgery. The Nationals rank fifth here, because the system doesn't love Jackson, forecasting him for a 4.21 ERA—in a pitcher-friendly park—and 0.8 WARP over 188 innings. Take the over on those latter two numbers; over the past three seasons, he's averaged a 3.96 ERA, 207 innings, and 1.9 WARP. Such is the nature of regression-based forecasting; we can quibble with many of these projections until the cows come home. The Nats are just 0.2 WARP out of a three-way tie for third with the significantly-improved Marlins, who added a starting pitcher from each side of Chicago via the incredibly stable Mark Buehrle and the incredibly unstable Carlos Zambrano.

To avoid repeating myself (and driving my editors crazy with endless table-setting), here's the master table, ranked by the combined WARP of each team's top six starters, and showing the total WARPs of smaller subsets as well.

Terrific Tandems: As with last year, the Phillies' one-two punch of Roy Halladay (2.75 ERA, 4.9 WARP) and Cliff Lee (2.92 ERA, 4.4 WARP) towers over the rest of the pack, though they come in nearly a full win below last year's forecast, which they fell short of by more than 1.0 WARP (9.0 vs. 10.3). Again running second is the Giants' twosome of Tim Lincecum (2.64 ERA, 4.6 WARP) and Matt Cain (3.05 ERA, 3.4 WARP). The Nats rank a surprising third on the strength of a nearly off-the-charts forecast for Strasburg, who's projected to lead the NL in both ERA (2.34) and pitching WARP (5.1) despite a modest total of 168 innings. The Nats have already decided that he'll be on an innings cap since he didn't pitch a full season last year after returning from Tommy John surgery, just as tandem-mate Jordan Zimmerman (3.80 ERA, 1.8 WARP) was last year.

The Brewers' duo of Greinke and Yovani Gallardo (3.2 WARP apiece) are tied with the Dodgers' Clayton Kershaw (2.94 ERA, 4.1 WARP) and Ted Lilly (3.35 ERA, 2.3 WARP) for fourth, narrowly edging the Diamondbacks' fine pairing of Ian Kennedy (3.44 ERA, 3.2 WARP), and Daniel Hudson (3.42 ERA, 3.1 WARP). The Cardinals, who have Adam Wainwright (3.27 ERA, 2.7 WARP) returning to join Chris Carpenter (3.25 ERA, 3.3 WARP), are seventh, though that's provided the latter's bulging disc doesn't prevent him from reaching 217 innings—take the under there.

Bringing up the rear are the Astros, whose nominal ace, Wandy Rodriguez, gets an unflattering forecast for 1.4 WARP, just over half of his three-year average of 2.6; from a three-year ERA of 3.36, his forecast comes in at an eyebrow-raising 4.07. In the Astros' tandem o' Disastro, he's joined by Bud Norris (4.47 ERA, 0.6 WARP).

Big Threes: The spaced-out schedules of the best-of-five Division Series lend themselves well to power trios, and the Phillies assert their chances at an NLCS berth by widening their lead on the pack via Cole Hamels (2.99 ERA, 3.5 WARP), who gains ground on the Giants' Madison Bumgarner (3.38 ERA, 2.1 WARP). Shaun Marcum (3.67 ERA, 2.7 WARP) pushes the Brewers past the Nats, who have Gonzalez (3.88 ERA, 1.7 WARP) forecast for a bit of regression even while remaining in a relatively pitcher-friendly environment. The Dodgers push into fifth place via Chad Billingsley, who's projected to rebound at least somewhat from last year's disappointing 4.21 ERA and 1.0 WARP with a 3.67 ERA and 1.6 WARP. The Dodgers edge out their NL West rivals in Arizona (who add Cahill's 1.6 WARP) as well as the Cardinals (who add Jaime Garcia's 1.8 WARP). The lowly Astros, via the hapless J.A. Happ (4.54 ERA, 0.4 WARP), fall even further behind the pack, with the Padres—Volquez (1.5), Cory Luebke (1.0), and Tim Stauffer (0.7)—dropping to 15^th.

Front Fours: The plot thickens as we focus on the quartets that could potentially wind up in a best-of-seven playoff series. For the Phillies, both Vance Worley and Joe Blanton come in at 0.6 WARP, with less than a full complement of innings for either (168 and 144, respectively), while for the Giants, Ryan Vogelsong keeps pace with 0.6 WARP of his own over 180 innings—an extremely conservative forecast given the massive leap forward that last year's 1.7 WARP represents.

The Brewers gain some ground thanks to Randy Wolf, but perhaps not as much as they should; the 35-year-old lefty's 4.42 ERA and 0.9 WARP are well off his three-year averages of a 3.70 ERA and 2.1 WARP, done at a time when he's averaged a robust 214 innings (31 more than this year's forecast). Thanks to Jackson, the Nationals remain fourth, with the Braves finally climbing in to the upper reaches; between Tommy Hanson (2.7 WARP), Brandon Beachy (2.4), Tim Hudson (2.2), and Jair Jurrjens (1.8), they don't see much falloff from their first through fourth starter. The quartet could be higher as well, if Hanson (145 innings), Beachy (160), and Hudson (145) can exceed their projected innings totals, though Hanson's shoulder and Hudson's back aren't exactly minor boo-boos to be waved off.

Fab Fives: As the starting fives round out for the day-to-day grind of the 162-game season, the Phillies (Blanton or Worley, again), Giants (the inevitable Barry Zito), and Brewers (Chris Narveson) maintain fairly consistent distances from each other. Mike Minor (1.2 WARP in 148 innings) pushes the Braves into fourth place in this derby with an exceptionally strong forecast for a fifth starter. The Nats fall into fifth thanks to the weak forecast of John Lannan (4.56 ERA, 0.1 WARP in 138 innings); that's an ERA more than half a run higher than his three-year mark (4.03), though to be fair, it's in the vicinity of his much less impressive Fair Run Averages.

The Nats' total is just a whisker ahead of the Marlins, who beyond ace Josh Johnson (3.6 WARP) have very similar forecasts for their two through five—Ricky Nolasco (1.7), Buehrle (1.5), Anibal Sanchez (1.4), and Zambrano (1.2). There are more ifs than most built into that total; Johnson is forecast for 188 innings, more than triple what he managed last year before succumbing to shoulder woes, while the once-fragile Sanchez is down for 174 despite dealing with shoulder soreness after two strong seasons of 195-plus innings, and Zambrano's in for 144, around what he's averaged over the last three increasingly erratic years. At the other end of the spectrum, note that the Astros' grouping loses value relative to replacement level the further it expands thanks to Jordan Lyles (-0.3 WARP) and Hernandez (-0.6 WARP).

Six-Packs: It's inevitable that most teams will require substantial rotation input beyond their designated front fives. Last year, the 30 teams' top five starters (going strictly by total starts) averaged a combined 135 turns, leaving 27 per team (17 percent) for alternates. While the Phillies still get the overall nod, here we see a cluster between the remainder of the top teams.

It's worth noting that some of the pitchers whose totals are incorporated into the mix are swingmen whose relief work is lumped in as well (I haven't asked for projection splits). The low innings and WARP totals generated by that bullpen work shouldn't drive us too far off course, though. The Nationals' Chien-Ming Wang (0.7 WARP in 96 innings) and the Brewers' Michael Fiers (0.7 WARP in 57 innings) do the most to close the gap between their respective teams and the Giants. The Braves lose a bit of ground via Julio Teheran (4.36 ERA, 0.2 WARP), though it remains blissfully ignorant of the 21-year-old's six-homer debacle last week, PECOTA isn't optimistic about the 21-year-old righty's strikeout and walk rates.

Behind the top five teams are the Diamondbacks, who are currently forecast for Josh Collmenter to throw 130 innings at 0.9 WARP, with rookies Tyler Skaggs and Trevor Bauer both forecast for 48 innings and totals of 0.4 and 0.3 WARP, respectively. It's possible one of the kids could move more quickly up the ladder, though WARPwise, it's mostly a wash. Also nudging their way toward the top with a surprising leap are the Reds, whose fireballing lefty, Aroldis Chapman, is forecast for 1.8 WARP, via 98 innings and 11 starts—an aggressive total given his 0.7 WARP over 63 1/3 innings over one season and change, and one that raises an eyebrow; does anyone expect Chapman to maintain an 11.0 K/9 in a split role?

Beyond the valuations, it's worth a gander at the ERAs and peripheral rates produced by these sextets. Note how far the Phillies are ahead of the pack in the former, particularly once you consider that they play in a more hitter-friendly environment than most of the teams in the upper half of the rankings. Then consider that they came in at 2.86 last year.

The Phils blow the rest of the rotations out of the water thanks to their microscopic walk rate; the second-best team in that category, the Cardinals, is 0.75 walks per nine worse. The Giants, on the other hand, are in the bottom quartile in that category, yet ahead of the Phillies on both home-run rate (thanks to AT&T Park) and strikeout rate (thanks to Lincecum; Cain, Vogelsong and Bumgarner are forecast to dip below 7.0 despite finishing above that mark last year).

The revamped Nats rotation figures to improve markedly in strikeout rate. Last year's starters finished 15^th in the league at 5.7 K/9, but with the return of Strasburg and the additions of Gonzalez and Jackson, they're forecast for a middle-of-the-pack eighth at 6.6 per nine, the largest gain in the league. On the other hand, after leading the senior circuit at 7.9 per nine, the Phillies' starters are forecast to dip to 6.7. Some of that is regression to the mean; PECOTA is particularly skeptical that Cliff Lee can maintain last year's 9.2 K/9, forecasting a steep drop to 7.1, and likewise for Roy Halladay (8.5 to 6.9) and Vance Worley (8.1 to 6.1). If you want to believe those are overly pessimistic, consider the gap between the Phils and the rest of the league even wider.

Of course, starting pitching won't be the only factor in the NL East race, or any race for that matter; both the Phillies' aging offense and the Nationals' on-base percentage-challenged unit will play their parts, though it's worth noting that the latter is forecast to outscore the former by 15 runs (701-686). The starting pitching is still the key separator between those two teams, but credit to the upstarts, who have closed the gap considerably with a couple key additions as well as better health from their homegrown stars.