Actually, it was the media's fault, more than Ainge, who was not in a position to trade for Davis. The Lakers provided all the heat, in their desperate attempt to trade for Davis before the deadline. They wanted no part of competing with the Celtics for Davis.
All the mediatalk had the Celtics wanting Davis after the season. Perhaps Ainge leaked his wishes to the media--we don't know. But he wouldn't have mentioned his own players. That was either leaked by NO or created by the media. It was logical that Tatum and/or Brown would be part of a deal post season.
Tatum, Brown, Rozier and the rest couldn't help seeing this stuff, and as 20 yo kids, it affected their motivation. After all, they had led the team down the stretch to the East finals--even though they flopped the last game in that shocking loss at home to the Cavs.
The other key factor was the decision to start Hayward out of nowhere, with hardly any pre-season indication. No doubt with Ainge's appoval. My first thought was they are playing the money--standard procedure these days. The Red Sox do it, too. I questioned Stevens' pre-season at the time, focussing on 14th and 15th player cuts rather than the starting rotation. A sign, perhaps, that the starters were preconceived by he and Ainge.
So now they are in a real pickle. Ainge (I hope he's healthy--haven't seen a word about him in the media) now has to pick up the pieces. He can't really get better without Davis, and he needs Irving to lure Davis. He has the pieces to get Davis, but more importantly, the coach has to use Davis to fill their needs up front. In the paint. Not the perimeter. Ainge also has to get more NBA experience on the coaching staff and the front office. The media is saying there is too much Butler presence.
And, oh yeah, there's another wild card in the picture. Durant. What's he going to do? Chances are he stays with the Warriors, but his next choice back a few years was the Celtics. If Irving or Horford leaves (doubt he will), they might have cap space for him. But Stevens may have lost his luster with veteran players.