CC is correct below.

Even though these guys can play with their stick in both hands, there are only a few guys that truly can dominate another player going to their weak hand. Hopkins has this issue right now where all 3 starting attackman are left hand dominate and it limits a little what they can do on offense.

You correct it by moving guys around from attack to midfield or running an attackman out of the box to get matched up on a SSDM.

As for why Garnsey isn't playing as much, I can't tell you because I haven't watched enough ND games yet this season.