Rashard may have had the advantage in the regular season, but KG of the post-season is a different beast.
I expect the Celtics to treat Rashard like Jamison. Honestly, I don't see much difference...Rashard is a much better 3 pt shooter and he's almost an inch taller, but otherwise he's about the same. He's not a better defender, nor is he a better post scorer. He's also a much worse rebounder. He'll be harder to deal with on offense but I expect KG to have a similar advantage against him down low.
Rashard Lewis is a very good defensive power forward ... much to my surprise, he has been very effective defensively at the four.
Rashard's man-to-man defense has been above average (excellent against perimeter fours + face up fours + good against physical post players like Boozer) and his team defense has been very good (transition defense + P'n'R defense are excellent, defensive rotations are very good, can switch onto other positions and defend them effectively, closes down shooters very well, the main weakness being his lack of shot-blocking in interior defense) .
Lewis has also done a good job against Garnett for three straight years. Lewis is quick enough and long enough to take away most of KG's easy scoring opportunities in transition, pick and rolls/pops, face up opportunities and midrange jump shots. Lewis has also done a good job pushing Garnett high off the post, where Garnett tries to post up 8 feet from the rim but ends up getting pushed out to 14-17 feet by the time he makes the catch on multiple possessions.
Rashard Lewis isn't a stopper. He is not going to shut down Garnett. Just like Garnett isn't going to shut Lewis down. They are both effective defenders against one another
(defensive + physical attributes match well against offensive + physical strengths) but they are also both highly skilled offensive players who are very difficult to stop ... neither is able to shut down the other player
(although Kevin is a better defender vs Lewis than vice versa) ... but they are going to make one another work extremely hard for their baskets. Nobody is going to get anything easy. They are going to be able to contain one another and stop the other from consistently having big scoring nights.
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Unlike the past two rounds, there is no great matchup offensively or defensively for Garnett against the other starting power forward (Lewis). Nor is there for Lewis, Garnett is a very good defender against perimeter fours like Lewis. Garnett defends Lewis well and Lewis is an effective defender against KG.
There is a big advantage here for Boston, in this matchup (Garnett vs Lewis), but it isn't offense (Garnett's scoring) and it isn't defense (shutting down Lewis) ... what it is is rebounding.
Garnett needs to hit the boards and grab 10+ rebounds a night and build up a large positive rebounding differential versus Lewis (Lewis grabs about 6 per 36, if KG gets 10 per 36, Boston will be +4 on the boards in that one individual matchup alone).
Those four extra possessions are a major difference maker and could decide the series. If Boston get those rebounds, they stand a very good chance of winning this series.
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Garnett does have a matchup advantage offensively against Ryan Anderson and Brandon Bass. Anderson is a below par defender and Bass lacks the size to trouble KG's jump shot.
No matchup advantage offensively against Lewis, Gortat or Dwight.