I'm not a rat coach, I let you know that up front, but it seems to me you can keep doing what you are doing. If a new GR can be skilled up to where you like them in a couple of games, then eventually your linerats and SV will "catch up" just by hanging around. One will get +St, or just fail to get injured, or something.

If you are really wanting them to simply break 200, you will want to skill specifc linos, even if it risks the win, but if you keep trying to win, you will get there. My Blue Bombers are totally un-balanced, but they made it through continued slogging and I love James, even if he inflates the TR.