Here are some advanced stat lines.
VORP: 2.8, BPM 2.8, WS 7.3, PER 15.8 Net On/Off +3.4, RPM 3.00 (9.28 wins)
VORP: 2.1, BPM 1.6, WS 6.7, PER 14.9, Net On/Off +11.5, RPM 3.89 (10.52 wins)
VORP: 1.4, BPM 0.2, WS 4.8, PER 13.2 , Net On/Off +3.3, RPM 0.08 (5.23 wins)
VORP: 0.7, BPM -0.5, WS 3.1, PER 14.4, Net On/Off -3.2, RPM -2.16 (1.13 wins)
VORP: 4.0, BPM 4.2, WS 10.4, PER 22.2, Net On/Off +5.7, RPM 3.06 (9.45 wins)
Probably obvious, but:
Crowder 2015, Crowder 2016, AB 2015, AB 2016, Hayward 2016
Two things. First, there is literally zero evidence that Bradley is a better overall player than Crowder in terms of what they have done on the court over the last two years for the Boston Celtics. And no, it's not all tied up in his injury time missed. You can say that true wings have a better time in the NBA and Bradley is more like a combo guard and that's fine. but that's all included in value, even if it's not Bradley's "fault"
Second, Hayward is clearly better...but not so much better than Crowder that we can sit around screaming in glee about getting Hayward for "free," if indeed Crowder is the sacrifice to clear cap space. Crowder plays good defense, spaces the floor, and doesn't turn the ball over. These are things that everyone misses when they just caterwaul about missed 3's or whines when he's getting steamrolled by LeBron, and they have what are tangible effects on the Celtics results.
Now, I said elsewhere the IT injury probably means that you need to work harder to keep competent guards around, and I mean it. But celebrating losing Crowder or thinking it's NBD flies in the face of any serious look at what has made the Celtics successful.