This is coming from Billy Wagner(notes), who was a teammate of Johan Santana(notes) and has seen plenty of CC Sabathia(notes).
Jon Lester(notes) of the Boston Red Sox, Wagner said, "is probably the best lefty in baseball right now as far as stuff. Santana, nothing against him, but I never saw him throwing in the upper 90s and spotting it, throwing breaking balls and changeups and spotting it.
"There is nobody in the two leagues that I’ve seen that can match [Lester’s] stuff. About the only other guy, and he’s a right-hander, is Josh Johnson(notes) with the Marlins."