It can affect the size of the sweet spot, depends on the bat though. I went from using my 01 ESTL to my 08 RockeTech, which was going from a 15" barrel to a 12" barrel, and was able to adjust to the smaller barrel in one BP session. More than anything, the difference was the LOCATION of the sweet spot. With a 12" barrel, the SS is closer to the end of the bad whereas with a larger barrel it will usually be farther down.