in my opinion, sports is one of the few subjects that does not benefit from IS - shutter speed is determined by requirements for action which will invariably be significantly higher than required by hand-hold
i'd recommend the 70-200 f4 without IS (unless you have other applications that will benefit from IS) and you will get sharp images wide open at 200 for a pretty reasonable price -- the 2.8 will provide less depth of focus, but otherwise i doubt anyone will see a difference in the images