There are no guarantees on where any team is going to finish so there is no point in tanking. Heck the 1 seed is in play. Miami's schedule is pretty tough and they only have a 2.5 game lead. Their schedule is: GS, NY, BKN, SAC, @ BOS, @ CHI, @ TOR, CHA, ATL, @ ORL
It isn't totally out of the realm of possibility that MIL or PHI falls to 5 (with CHI at 3) and the other ends up 1 with BKN at 7. Thus by being the 4 seed, Boston might end up playing Philly, Milwaukee, and Brooklyn.
Also, tanking last year cost the Clippers as they had that very difficult 1st round match-up which seemed to wear Kawhi down and then he ended up getting hurt. Perhaps if they didn't throw the games at the end of the year, we are talking about the Clippers as the defending NBA champs with them looking like clear favorites to repeat because Kawhi never gets hurt.