nERD of 2.56 - meaning Cain gives up an average of 2.56 runs per game fewer than a league average pitcher over a 27-out performance - throughout his career. This year, that number is way down, to 1.29. His ERA is 0.79 runs per game higher, his strikeout rate (K%) is down, and his walk rate (BB%), Wins and Hits per innings pitched (WHIP), Fielding Independent Pitching (FIP) and home runs allowed per nine innings (HR/9) are all up.

And as you can see, Cain's batting average on balls in play (BABIP) of .265 is right in line with his career mark, meaning he hasn't been suffering from abnormally bad luck. Those numbers indicate Cain has been hurting, but it's also a bit worrisome coming on the heels of a 2013 season which also saw some of his numbers worse than his career averages.

While the drop off wasn't as severe as this year's totals, his 2013 nERD was 0.75 lower and his ERA was 0.61 runs a game higher than his career average, and his FIP and HR/9 were a bit off as well, but not by much. However, his K%, BB% and WHIP, all very important indicators that give a good impression of a pitcher's true performance, were all slightly better than normal. And in '13, his BABIP was almost right on his career mark, so, again, it doesn't appear as if he was any unluckier than in previous seasons.

Most saw his drop-off in 2013 as a result of a bad defense playing behind him (the Giants turned just two double plays for him all season), and an offense that didn't support him (just 3.4 runs per game), and the stats seem to bear that out. But when taken together with his struggles in 2014, some are wondering if a true regression, spawned by injury, is starting to set in at age 29.

Yusmeiro Petit will make Cain's start for him tonight in Philadelphia. Petit is 3-3 with a 3.86 ERA this year, shuttling back and forth between the bullpen and the rotation (26 appearances, 5 starts). And as of right now, the Giants aren't losing much by substituting Petit for an injured Cain. Petit's K% is 25.7%, and his BB% is 5.8% this year, both far better than Cain's '14 numbers. And his 3.86 ERA, 3.05 FIP and HR/9 rate of 0.86 are also superior to Cain.

But here's a quick word to the wise for you daily fantasy players. While the Phillies have struggled offensively at home this year, Petit has a 7.71 career ERA against them. In 11.2 innings against the Phils, he's given up 10 earned runs, 17 hits, 6 walks and 4 home runs. He may not be a great play tonight.

Tonight will likely be Petit's only start for a while. Cain's DL stint is retroactive to July 11th, and the team says he will make his next start on Sunday. Will that be enough rest to fix him? Or will the Giants have to seriously investigate the starting pitching market this month, perhaps trying to make a play for David Price, Ian Kennedy or Cole Hamels?

My belief is Cain's 2013 season wasn't as bad as some of the more traditional numbers would make it seem, and that his issues this year are solely because of his "cranky" elbow. And even with that "cranky" elbow, Cain's velocity is right where it has always been. However, that elbow should have the Giants concerned, in light of the money they have invested in him. And even though they are in the midst of a bitter fight with the Los Angeles Dodgers for the National League West, it would be wise for them to investigate the trade market and handle their ace right-hander with care.

Once Cain is healthy, I expect a return to his pre-2013 numbers. But that may not happen this year.