Obviously it's a little too late on Vazquez, but Hanson is always a solid choice to play, and should hopefully narrow the gap in ERA and WHIP (although I'm playing a guy who has him, so hopefully not!
I have De La Rosa and not too sure I trust him on this one. I'm losing 2.077 to 1.790 and ERA and only slightly winning 1.101 to 1.110 in WHIP, so those two categories are basically a toss-up. I think he has a decent chance to bring your ERA and WHIP down though, so I say start him. In my case, I think he has a decent chance to bring mine up and out of contention.
Penny is @SF by the way (I'm starting him).