There are many different ways of measuring a pitcher's effectiveness. Earned Run Average is a popular method, as is walks + hits divided by innings pitched (WHIP). While those may carry some weight for baseball fans, they don't necessarily have much merit for baseball bettors, who are solely concerned with which team wins the game.
A pitcher's win-loss record only tells half the story in that it just specify the games in which the pitcher received a decision. As a bettor, it makes no difference which pitcher is credited with the win. As long as you win your bet, it does not matter if the starting pitcher earned the win or one of the relief pitchers.
For bettors, instead of looking at a pitcher's win-loss record, a better statistic is known as Team Record in Games Started, which is often abbreviated as TRGS. It credits a pitcher with a win when his team wins the game, regardless of which pitcher earned the decision, while it hands the pitcher a loss when his team loses, even if the bullpen gave up a four-run lead in the eighth inning.
Using TRGS instead of the traditional win-loss record will often allow you to find pitchers who are likely to be slightly over-valued or under-valued depending on their team's record in games where they did not earn a decision. Many times a pitcher's win-loss record and TRGS will be fairly equal in that a pitcher with a 10-10 record will have a TRGS of 14-14, but there are also times where they can differ greatly. This is where bettors who incorporate TRGS into their handicapping can gain a bit of an advantage.
2013 was considered a bit of an off year for Detroit's Justin Verlander, who finished the season with a 14-13 record and a respectable 3.32 ERA. But Detroit was 1-9 in games where Verlander did not get the decision and his TRGS was a poor 15-22, which gave him a flat-bet loss of 23.4 units, which was the first time a pitcher had shown a flat- bet loss of over 20 units since David Cone did so in 2000. It was also the second time Verlander has led the league in money lost, having pulled off the dubious feat in 2008.
Other pitchers, such as Matt Cain (8-10 win-loss record, 11-19 TRGS) and Felix Hernandez (12-10 win-loss record, 14-17 TRGS) also were among the league leaders in money lost.
Likewise, there are pitchers who see a great improvement in TRGs over their win-loss record, such as Ryan Dempster. In 2013, Dempster was just 8-9 with a 4.64 ERA, but his TRGS of 17-12 allowed him to show a modest flat-bet profit despite posting dismal traditional numbers. Derek Holland had a 10-9 win-loss record, but a 20-13 TRGs, making him a decent bet, while Arizona's Pat Corbin had a solid 14-8 win-loss record, but an even more impressive 23-9 TRGS, making him one of the top money earning pitchers for the year.
TRGS is a better way of looking at a pitcher and those who use it in their handicapping have an advantage over those who do not, and as you know, bettors can use every advantage that they can get.