First, let's get real: the Hawks aren't going to win their series vs the Celtics (currently even at two games apiece). But in winning games 3 & 4 on their home floor, the young Hawks made a critical step towards eventual championship contention. How did they do it? Dave pointed to their athleticism and unselfish team play. But I think you need to add TOUGHNESS.
Game 3 was a fluke: the Celtics went in overconfident and didn't give their best effort. But Game 4 was another matter. I felt the play when Garnett threw the elbow at Pachulia was pivotal. (Magic Johnson concurred post-game.) The young Euro shot one quick look at the nearest official and saw he wasn't going to do anything, then he took matters into his own hands. He went right up to Garnett and not only got in his face but practically head-butted him. Garnett had no doubt been thinking this is another soft young Euro that I can intimidate, and he learned otherwise. Garnett probably didn't realize that was a SOVIET (Georgian) Euro he was messing with! Recall that Garnett pulled the same thing on the young Blazers this season and they failed the test--allowing him to get into their heads.
I hope the Blazers watched that Hawks game and absorbed the lesson. To compete at the highest levels in the NBA, you must show in no uncertain terms that you can't be intimidated. Talk isn't enough: Pachulia actually made Garnett back up, and at that moment the dynamic of the series shifted. He didn't have to throw a punch: Garnett knew in his bones that if he did anything, this guy was going to respond in kind. The sequence was reminiscent of the Blazers' championship season when Lucas confronted Dawkins.
If the Blazers DID see the Hawks game and absorb the lesson, then they'll be an important step closer to becoming a contender. That is, if they have the toughness to do what the Hawks have done. (Importantly, it hasn't just been Pachulia who's shown a willingness to stand up to the Mighty Celtics; remember Horford answering the Celtics' trash-talking with some of his own at the end of Game 3?) Certainly Jack and Przy are tough guys, and I'm not worried about Oden. Even LMA seems willing to stand up for himself; he just needs to keep filling out so that he can back up his attitude with more physicality.
But the jury is still out on the rest of the team. Are they ready to do what the Hawks have done and announce to the league that they're not a "soft" club that can be intimidated? It's past time for them to do so. We should learn something when the Blazers play in Boston next season, because as sure as the sun rises in the morning, Garnett & Co. will test them once again.