Gabino was not getting his bread and butter pitches called strikes
Here is Gabino's Pitch F/X location data from last nights game (from Brooksbaseball.net):

Gabino's bread and butter are pitches in the red rectangle. For Gabino to be successful, he needs those to be called strikes. Gary Darling, the home plate umpire did not only call pitches down and out of the strike zone balls, but some in the lower part of the strike zone as well.
Gabino tried to adjust and was successful on the outside part of the strike zone (red squares to the left), but he left too many balls in the middle that resulted in being in play (blue squares)
Darling had a consistently small strike zone (here is his balls and strikes calls for all pitchers from both teams) :

Gabino threw very few changeups
Gabino's best pitch is a circle change. Last night he threw only 8 change ups in 57 pitches (and 3 of them in a row at some point in the third inning.) I am not sure whether this is due to the fact that the last time Joe Mauer caught him was in the Spring Training of the 2008 season, but for Gabino to be successful his change up ration should be higher and better mixed.
Gabino had a mechanical issue of sorts
Here is Gabino's release point from last night:

Very inconsistent, and it seems to form 2 nuclei very similar to Liriano's. Liriano's release point is different when facing RHB and LHB (because he steps on different place on the rubber depending on whether he faces a lefty or a righty), but Gabino's was all over the place regardless whether he was facing a lefty or a righty.
As you can see he releases his breaking pitches (orange) and change up (yellow) from a much straighter position than his fastballs (green and blue). This is a huge difference and easily picked up by an opposing batter who can wait on a pitch based on Gabino's release point.
He is tipping his pitches in a very bad way... When a ball comes from a straight delivery, the opponent can guess slider or change up and when it comes from a 3/4 delivery he can guess fastball and be right 100% of the time.
Not too good.
Gabino needs to fix these 3 things in order to be a successful major league pitcher:
- Adjust when he does not get the low strike, but do not throw the ball in the middle of the plate (his 93 mph max FB is not good enought to blow by batters). Stay on the edges, like he partially did last night
- Mix it up. Got to have batters beat him with his best weapon (change up) not with his least (fastball)
- Get a consistent delivery and release point to improve his command and stop tipping his pitches



