Lately, many Red Sox fans (myself included) have been pushing for the Sox to sign a big-name pitcher like Roy Oswalt or, until recently, Edwin Jackson. I would love it if they did that, but the likelihood of that happening is very low at the moment. Therefore, today I will look into how the Red Sox could do with one of Vicente Padilla, Aaron Cook, or Carlos Silva rounding out the rotation.
First, let's look at Vicente Padilla. Padilla has not seen a whole lot of time the past few years, as he has been derailed by injuries in 2011 and 2010, pitching in just 9 and 16 games, respectively. So, let's head back to his 2009 season, which he played for the Rangers and Dodgers. In that season, he went 12-6/4.46/97. His peripherals showed that he pretty much deserved those numbers, with a 4.45 FIP and 4.36 xFIP. His K/9 at 5.93 and BB/9 at 3.30 were both slightly worse than his career averages. His BABIP of .305 was pretty normal that year. His career stats show a 4.31/4.43/4.39 pitching line plus 6.33 K/9 and 3.17 BB/9. Overall, for a #5 starter, an ERA around 4.50 and something like 6 K/9 would be very acceptable.
Next is Aaron Cook, who was one of a group of solid, good pitchers from about 2004-2009 until injuries derailed his career. In 18 games with the Rockies in 2011, he pitched to an unimpressive 3-10/6.03/48. However, his peripherals show that he shouldn't have been nearly as bad-- his FIP was 4.54 and his xFIP was 4.37, not too far off of Padilla's. However, his strikeouts have never been impressive, at just 4.45 in 2011 paired with a walk rate of 3.43. Still, the one thing Cook has always been able to do is make batters hit it on the ground. The sinkerballer's striking 55.1% ground ball rate in 2011 was actually lower than the 57.4% in his career.