How do you solve a problem like Matthew Cain?

Matt Cain made a rehab start in Fresno for the River Cats on Saturday, and it did not go well. The line was already not encouraging – 5 IP, 10 H, 6 R (4 ER), 4 K, 2 BB – but then you have this worrying nugget from the Fresno Bee:

His fastball velocity started about 90-92 mph but dipped to the mid- to high 80s. Cain also missed location on some offspeed pitches.

And then this one, which on its face isn’t as bad, but when you think about it, oh boy.

"My body felt good, everything came out of it good," said Cain, on the disabled list since Aug. 18. "I thought I was locating well. Even some of the pitches they got hits on were located well.

Because if he was making the pitches he wanted to make and AAA hitters were hitting them, it’s not likely that those pitches will work in the majors. Making bad pitches that get hit because of rust or working through an injury is one thing, and you don’t really want to see it, but it happens. Making good pitches that get hit in AAA is a bad sign for what you’ll do in the majors.

So now what? With Jake Peavy on the DL and Albert Suarez looking unimpressive against the Braves on Saturday, the Giants need a fifth starter, but, well, there’s no reason to trust Cain with the start either. In 17 major league starts this year, he’s had a 5.81 ERA and a 5.38 FIP. In 2 AAA starts this year, he’s had a .506 ERA with a 5.23 FIP. His last start in the minors was very bad. His last start in the majors was very bad. He is apparently able to throw 5 shutout innings against the Nationals at will, but otherwise, his season has been a disaster. The team wouldn’t put him into the rotation to face the Sonoma Stompers, much less the Cubs in Wrigley Field.

Does Cain go to the bullpen? He pitched in relief twice last year, and was not especially effective then. Does he stay in the rotation? He hasn’t been above replacement level since 2013 and he hasn’t been good since 2012, so no, that doesn’t look like an answer. Do you call him up when rosters expand, stash him on the bench, and give him those Cory Gearrin innings at the end of blowouts? Yes, probably, but that’s not going to fix him or help the team, any more than it did last year.

If you want to complain about his salary here, this is the part where I will point out that Matt Cain has earned every cent he’s making because the economics of baseball are screwy. In 2009, he pitched 217.2 innings with 1 2.89 ERA, good for an ERA+ of 147. He made less than $3 million. The reason that was possible was that players get paid too much for their decline years. Matt Cain did good work for a bad system with the belief that the system would one day repay him for that work, and he was right. This is the money he should have been making years ago. He couldn’t have it then, so I’m glad he’s making it now.

As for next year, who knows? 2017 is the last year on Cain’s contract (unless they pick up his 2018 option!!!!!!) and the Giants, as a rule, don’t cut their generation-defining players, even when they’re way, way past their primes. So will 2017 just be another lost year for Cain, waffling between injury and ineffectiveness, occasionally tempting us all (read: me) with several starts of sustained competence before turning back into this other guy who’s been hanging around since 2014? At this point, it looks likely. And sad. Mostly sad.