looks like a good plan. Mabry is a winner in Shea. He did this for me once in 2005:
[code:1:080babbd5a] AB R H 2B 3B HR RBI BB SO BA OBP SLG
404 70 131 15 1 28 84 36 110 .324.384 .570
[/code:1:080babbd5a]
Didn't pick him up til a few games in, and then he got hit with a few long term injuries which summed up my luck on this team, but he'll do great for you. Hafner obviously is a monster.
There are lots of midrange RH RPs who do well against LH hitters for a good price, and Duch is one of them. Meadows, Adams, etc there are many.