Cubs announcer Pat Hughes brought up an interesting observation.
There has been some debate recently on whether "wins" is a good measure for a starting pitcher's performance. In the age of sabermetrics, wins seems to be an unconditional after thought.
Hughes brought up the point that if a starting pitcher has a record of 18-8, that means that his team has won 10 more games with him on the mound. Therefore, if the rest of the team went .500, the team would end up the season 10 games over .500 (and probably in the playoffs)
It would also mean that pitcher would be the team's most valuable player.
Hughes was referencing Johnny Cueto, who was 18-8 at the time. After the loss to the Cubs, Cueto still has a 6.1 WAR for the season. That is six games above replacement value.
Other pitchers with large W-L variables include Clayton Kershaw who is 19-3, with a 7.6 WAR.
Chris Sale is 12-3 with a 6.5 WAR. Felix Hernandez is 14-5 with a 6.8 WAR. Corey Kluber is 16-9 with 6.3 WAR.
The Win Variable to WAR:
Kershaw + 13 = 7.6 WAR
Hernandez +9 = 6.8 WAR
Sale +9 = 6.5 WAR
Kluber +7 = 6.3 WAR
Cueto +9 = 6.1 WAR
The top five pitchers in the majors have a win differential of +47 and WAR of 33.3.
WAR/Win Variable = .709 wins above replacement ratio.
There may be other factors on a starter getting the ability to get wins, foremost, the ability to pitch deep into games. There also may be a psychological team effect that fielders will play better when they know their "ace" is pitching.
What about other good pitchers?
Madison Bumgarner is 18-9 with a 3.7 WAR or .411 wins above replacement ratio.
Jon Lester is 15-10 with a 4.2 WAR or .840 wins above replacement ratio.
While league average changes on a year-to-year basis, replacement level
stays the same: a .380 win percentage is the replacement level for starting
pitcher.
FanGraphs and Baseball Reference calculate pitching WAR differently.
BA Computing WAR: starts with runs allowed by
the pitcher and compares it to the league average pitcher (adjusting for
quality of opposition), parks pitched in, and quality of defense behind
the pitcher.
WAR = WAR_rep + WAA + WAA_adj
FanGraphs Pitcher WAR:
FG begins with FIP, which is a fielding independent
pitching stat comparable in scale to ERA that is computed using only
pitcher dependent stats.
FIP = ((13*HR)+(3*(BB+HBP-IBB))-(2*K))/IP +
lg_specific_constant(around 3.20 or so)
In FIP, hits allowed and non-strikeout outs recorded have no role
in the calculation other than in the number of total innings pitched.
The assumption is that once the ball is put into play (other than a
home run) the entire outcome is determined by random chance and team
defensive quality.
So even the stats gurus cannot agree on the best formula to determine how well a starter pitcher is to his team. So maybe Hughes has hit upon the simplest comparison possible: the pitcher's win differential since the single goal in any game is to win.
