I was at game 3 and saw 4 as well...both were very winnable, but Nets couldn't close out
Reasons Nets lost:
Game 3
Kristic couldn't hit any open jumpers (there was a stretch where he mised at least 7 wide open jumpers in a row)
Carter's series of turnovers (plus Kidd's one) late in the 4th
Richard Jefferson's disappearance (after scoring 17 in the first half)
Vaughn's stupid fouls (at least 3 touch fouls within 2 minutes) that put Miami over the limit early in the quarter
Game 4
Vince Carter was completly outplayed by Wade
Richard Jefferson disappeared once again
Nobody on Nets can consistently shoot when open
Really though, the Nets could easily have won both those games but as long as their defense concentrates on Wade/Shaw...players like Walker and Posey will get open threes. Conversely, on the other end, when Haet double Carter or Jefferson, the Nets always have at least one player who couldn't make a shot if his life depended on it (like Collins or Vaughn or John Thomas...even Lamont Murray to a lesser extent). Thus, Carter and Jeffesron are made ineffective while nobody else picks up the slack whereas Miami can win with both Shaq and Wade scoring below their season averages.