Perk should never have been put on Z-Bo in the first place. He simply doesn't have the quickness or agility to cover an offensive threat like Z-Bo.
Randolph's jump shooting, pick and roll/pop game, ability to put the ball on the floor and drive + Randolph's superior quickness/agility make Perk an ineffective defensive matchup.
Leave Perk on Marc Gasol. A player who he can actually defend.
Yet he guarded D Howard? Howard is much more the athlete then Z Bo. I never saw Perk guarding him... It was always Ibaka. Zbo is being overrated for his perimeter skills here. He is beast in the paint, but Perk can defend him. I saw Sheed play very well against Randolph last year when we played them. Perk can hold his own.
Dwight Howard has the athleticism but not the skill-level / skill-set.
Howard doesn't have the ability to face up from 15-20 feet and be a triple threat. Not like Z.Randolph.
And in years past, Howard lacked the footwork on his post ups to take full advantage of his quickness closer to the basket. He relied on a power game. Although he has improved in this regard this season.
And like Perk could defend Dwight's power game ... Perk can equally well defend Zach Randolph's power game in the post. However, Perk cannot defend Randolph once he steps away from the rim and puts him in pick and rolls/pops + face up opportunities.
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Athleticism without the skill-set = no advantage
Athleticism + skill-set = advantage