'+' plays take away hits, so no, your '+' plays would not go up with more balls put into play, because those extra balls put into play due to low K's have already been predetermined to be "outs". The fielder can still make and error on a fieldable ball, but there is no hit to take away. I could be wrong, but thats the way I understand it, and it would make sense.
Also, if your SS is playing any games at 99% or worse, your fielding% will drop dramatically. Play him at 100% only.
Also, the year of your pitcher matters some, but I suspect most of the other teams in your league have those same pitchers as well.