Blog post

July 16, 2016 [LINK / comment]

The Nationals' starting rotation

NOTE: The analysis below pertains strictly to the 90 games played before the All-Star break. I'll discuss the ongoing series against the Pittsburgh Pirates tomorrow.

A major reason for the success of the Washington Nationals' during the first half of the 2016 season has been the remarkably consistent performance of the five pitchers who comprise their starting rotation: Stephen Strasburg, Max Scherzer, Gio Gonzalez, Tanner Roark, and Joe Ross. (Scherzer was slated to be the team's ace pitcher this year, but Strasburg has outperformed him in most categories.)

NOTE: The above figures do not include the two games started by Lucas Giolito (4 IP, 3 2/3 IP) and the one game started by Yusmeiro Petit (6 IP).
SOURCE: MLB.com, plus my own daily tabulations of game results.

Those grades take into account the expectations for the individual pitchers, and are almost identical to those published in the Washington Post Kids Post section on Thursday. They gave Gio Gonzalez a D, which is a bit harsh.

In particular, the endurance of the Nationals starting pitchers -- as measured by number of innings pitched per game -- has been simply amazing, as I discussed on June 7. This chart compares that factor to the run differential in each game; positive = win, negative = loss.

How much does innings pitched matter, statistically speaking? The correlation coefficient r between that variable and the margin of victory (or defeat) variable is 0.261, which yields an R² value of 0.0676 -- not very high, but far from negligible. (That means that 6.76% of the variation in the run differential can be explained by the number of innings pitched by the starter.) Multiple regression analysis might help to sort out the relative importance of pitching, batting, fielding, etc., but that is beyond my scope for now.

The only complete game pitched by a National this year was on May 11 (see May 23 blog post), when Max Scherzer struck out 20 Detroit Tigers batters, and yet barely held on in the ninth inning to win the game, 3-2. (It almost happened again tonight...)

Of the 90 games they played this year before All-Star break, in only 20 has the starting pitcher not lasted at least six innings. Among the notable lapses by Nats starting pitchers:

Otherwise, with few exceptions, Washington's starting pitchers had "quality starts," i.e. at least six innings pitched with three or fewer earned runs.

As the (symbolic) second half of the season begins, things are looking very good for the pitching staff, subjectively speaking. Stephen Strasburg shows occasional signs of fatigue and stress toward the middle of games, especially on the hot and muggy days for which Washington is famous, but he seems to have matured enough to know when he has had it. Max Scherzer has not let the occasional disappointments affect his positive outlook, and he has a solid psychological core to "go the distance" into October. Likewise, Tanner Roark is a veritable bulldog on the mound, with good pitching "stuff" and usually a steady temperament. Joe Ross was superb for a rookie pitcher late last season, effectively replacing Doug Fister, and he was excellent for the first several weeks of this year. Time will tell whether he gets over his injury and resumes performing at a top-notch level. His temporary replacement, Lucas Giolito, is touted as the Nats' ace of the future, but still needs polishing at the minor league level. He will probably play in more games after the September 1 roster expansion, perhaps earlier. The big question mark is Gio Gonzalez, the archetypical "head case." One or two things go wrong in the early innings, and he's a mess. It may be the fact that this is the last year of his contract, much like the "final year" pressure evidently ruined Ian Desmond's performance at shortstop last year. But he was the first National to win 20 games in a season (in 2012), and he has at least a few more good years in him -- either in D.C. or elsewhere.

ASG 2016 gripe

In my post about the All Star Game, I neglected to mention something that I wrote on Facebook. In the top of the eighth inning, the National League had the bases loaded, and Aledmys Diaz came up to bat. He took ball one, and then the second pitch which was clearly outside, but the umpire called it a strike. So Diaz felt obliged to swing at the third pitch, which was low, and then he struck out. On that one at-bat hinged the outcome of the whole game, and that umpire's call was a real shame.