In his last start, Santana tossed 4 no-hit innings against the Red Sox before a rain delay that ended his day. Floyd has had a couple of bad starts, including his last one (6 ER, 6 IP vs. Baltimore). He's also had some excellent starts, including his second-to-last start (2 ER, 8 IP, 10 SO, 1 BB at Yankee Stadium.
Floyd has only finished with an ERA under 4.00 once (2008: 17-8, 3.84), but he has improved on his strikeouts, walks and hits allowed over previous years so far in 2011. Santana has been inconsistent throughout his career, usually underperforming just when it looks like he's about to break out and become a top-line pitcher.
That might happen again this year, but he is clearly better than a 4.43 ERA and maybe his last start was the first step in getting on track. The pressure should be off a little bit this year too, with Haren and Weaver leading the Angels rotation.