Kepler really improved his hitting against lefties last season and kept it rolling through this year, but it did take him a big portion of his career to do it.
I don't think it's as much as the Twins being predictable as it was a prime situation for Tampa. 2 run lead in the 5th with 2 lefties coming up. If Diekleman gets Max, I have no doubt in my mind that AK is hitting in the 6th no matter who is pitching. Using Solano, who is much better at hitting lefties there gives you a better shot at the lead. Not to mention Solano doesn't have near as much trouble hitting RHP as AK does hitting LHP, so having him hit against a righty later isn't as big of a deal.
If this game is in May, I also think AK gets the AB. With the division title in reach, Rocco choosing to go for the lead earlier in the game seems warranted.