The Cal League isn't really offense happy -- that's an old stigma it still carries but just doesn't ring true anymore as teams have moved into different stadiums. These days it's got some extreme pitcher parks and extreme hitter's parks but overall it tends to play pretty neutral to pitcher friendly. IE's HR index for LHB is 75, for RHs it's 60. Those are pretty extreme values.. Rancho Cucamonga sits at 85, Lake Elsinore - 76.. The only hitter's park in the southern division is Lancaster which is ridiculous with a HR index of 159. Up north you have two parks over 100, Visalia at 120 and Stockton at 119, the other two are are extremely slanted towards pitchers - Modesto's at 57 and San Jose at 81. When it's all said and done 5 of the 8 teams play in parks with a HR index about 20 points below the average.
When you look at Thaiss you have to look at the predictive rates -- his K rate is 10.7, the league average is 17.7. His walk rate is 14.5, the league average is 10,0. His pulled FB% is 49% vs a league average of 42% and his LD% is 5% above the league average. All of those numbers are pointing in the right direction... The pulled FB% is a good sign as far as power goes -- it tends to mean he is able to turn on pitches which directly leads to power output.