It's really unfortunate that the sports media fabricates drama out of thin air. Calling the Celtics out for "tanking" is complete non-sense. I think Celtics fans know that their coach and team always try to win each game. The Celtics do their best with a mediocre roster.
The real issue of tanking is the issue of deliberately not putting together the best team possible. This is a legitimate concern. It's a strategic choice from the owner and management that they'd rather sacrifice some number of wins in the present season for the increased chance of getting better draft picks in future seasons (and therefore winning more games in the future). So the real issue of tanking is that some people think that teams should 1) always maximize competitiveness in the present season and 2) therefore try to win as many games as possible in the present season.
I'm not sure where I come out on this issue. The aforementioned "tanking" strategy certainly blunts competition and may curtail fan enjoyment in the present season. But isn't part of being a fan that we always look to the future in the hopes of getting one more great player and then attaining greatness? A tanking strategy in the present season would certainly provide fans with hope for the next one. But one thing I'm certain of is that accusing a team like the Celtics of not playing hard, of tanking, is just plain wrong.