There is no such thing as a streaky player.
This has been studied to death by armies of mathaticians who should have better things to do.
Periods of hot and cold hitting are just a reflection of the natural variability observed in coin tossing. A good hitter has a better chance of a hitting streak just because he will get more hits and the chances of clustering are higher.
So slotting someone in who is "hot" is just as likely to backfire as it is to pay off. Sure all of us have occassional anecdotal experiences that seem to defy this, but it's a fact.
(Now if I could only convince myself of this as it applies to Eric Chavez .
This simply isn't true. Yes, random things tend to have many more "streaks" than people expect from something that is truely random. But baseball players hitting well is NOT random. It could only be random if they were doing the exact same thing at every at-bat, but they're not. When a player gets hot, he's more relaxed, his swing is automatic and unforced- a product of muscle memory, and his reaction times are quick. When he's in a slump, his swing is forced, he's thinking too hard and not letting it happen, and his mental attitude makes it harder for him to get a hit. To say that a baseball player's evolution through the season is an independent random variable is a ridiculous hypothesis.
edit: I bailed on Burrel a week and a half into the season. It would have been perfect timing, except I got Magglio Ordonez for him, two days before the "hernia"