I can't believe how short people's memories are.
In 2008 we won a title with KG closing out games with a 6-8 220 lb SMALL forward playing the PF spot.
Since then, we've routinely run out lineups with other undersized PFs like BBD, Powe, and Jeff Green out there with KG.
This is nothing new. We've been doing this the entire Big Three Era. If anything, West is an upgrade over these guys as he probably has an inch or two on BBD and certainly has a lot more muscle than Posey or Green.