I'm of the opinion that chemistry is the result of winning, rather than the other way around. As far as Theriot/Cedeno goes... Coming into the year, there was a choice between two below average in-house options for SS. Cedeno was a younger player with better tools that looked awful in the majors for a year, but looked fantastic in the minors last year. Theriot was two years older, tired at the end of last year, and never had very impressive minor league numbers. Either way you go, you take a risk, and some would've rather taken the higher risk/higher reward player over the player with a decent chance at mediocrity. Offensively, Theriot has been solid this year because he's hit more line drives, and earlier in the year he was being a lot more patient. Lately, his patience has been down along with his walk rate, but I'm not sure whether that is more due to pitchers challenging him more, or him swinging at more pitches earlier in the count. Cedeno started out with unbelievable patience and was spraying line drives all over the field. Both have tailed off significantly as his patience has all but disappeared, and as a result pitchers don't feel the need to throw him strikes, as he'll get himself out. Defensively, if he gets to a ball, he'll get it cleanly. His range is below average, and his arm is below average, which would indicate he'd be better suited as a second baseman defensively. Contrast that to Cedeno, who has better range and a stronger arm, but is more prone to misplay a ball he gets to. So, really, the choice there is whether it's better to get to more balls and have more errors than have more balls get through the infield, but create fewer errors. Six of one, half-dozen of the other. So, then, obviously, Theriot has had the better year overall, as he hasn't tailed off offensively yet. If he wants to continue to be a reliable part of the offense, he'll need to keep hitting LDs at the rate he has, or improve his patience at the plate to where it was earlier in the year.