Doc Rivers has come up with some pretty darn good inbounds plays, both in the regular season and in the playoffs. Also, even if a defense knows a play is coming, it can still work if executed properly.
This is just an excuse by a fan upset about his team coming up just short of an improbable comeback. I didn't notice it, but in reading the Daily Dime on espn.com, McDyess was apparently wide open rolling to the basket and Ginobili missed him. So for all we know, that could've been one of Pop's best plays, but it just wasn't executed properly.