So who in the NBA, then, meets the definition of an always poor player?
It's obvious that professional players are good, otherwise they don't make an NBA team, don't you think? It goes without saying that Rondo can play better than he's playing now. Same for Pierce, Garnett, Allen, Davis, et al. But they're not.
I would anticipate that Doc, Ainge and the staff are looking for reasons why specific players - Rondo included - are playing at or near the worst levels of their career, not searching for alibis.
The true issue now is elevating the results this team produces. Rondo's career lows in play quality are part of that mix, but not all of it. In the meantime, what he and his teammates did last year means absolutely nothing, because none of them are approaching that level. Team sports is the here and now. Not yesterday.