When OKC first dealt Jeff Green for Boston's tough-minded, low-post defending center, the deal made some sense. Though Green was arguably the better player, the Thunder did not have an answer for Tim Duncan or Pau Gasol—two post threats they expected to see in the playoffs for years to come.
Serge Ibaka wasn't quite yet Serge Ibaka; Nick Collison, though very effective in short bursts, wasn't the answer. Oklahoma City simply couldn't handle teams with a significant presence on the block.
There was also the matter of Ibaka's future development as a whole: More effective as a weak-side shot-blocker working away from the ball in a helping capacity, Ibaka was stuck on more powerful centers and limited in his roaming of the paint.
With the arrival of Perkins, he could move over to the power forward position and guard the lesser of the opponent's two big men. This allowed him to primarily serve as a secondary defender, blocking shots and defending the rim as an always-looming presence any time the opponent attacked the basket.
Since Perkins' arrival, things haven't gone well. This season, the Thunder's once-starting lineup of Reggie Jackson, Thabo Sefolosha, Kevin Durant, Serge Ibaka and Perkins is a plus-81 in 525 minutes on the floor together, per NBA.com.
But that is Perkins' only appearance in the Thunder's best lineups—the next nine strongest Thunder units do not involve him.
Meanwhile, three of the Thunder's seven worst lineups involve Perkins. Keep in mind that he only plays 19.7 minutes per game, and so his continual appearance in poor Thunder lineups has greater significance.
The real sign of his impact on the floor can be seen in his offensive and defensive ratings. With a 102.7 offensive rating, according to NBA.com, he's only ahead of newly-signed Caron Butler and (now-released) Ryan Gomes. While his defensive rating of 100.3 is seventh best on the team, his net rating of 2.4 is third worst. In short, his limited defensive impact hardly outweighs the giant sacrifice on offense.
A few years ago, Perkins was a much more effective defensive player due to the structure of the league's personnel. An influx of athleticism and position-less talent has moved the NBA towards more hybrid lineups, neglecting the use of the prototypical back-to-the-basket centers.
Simply put, the majority of NBA teams don't have a true low-post threat through whom their offense flows.
The days of Tim Duncan, Yao Ming and Shaquille O'Neal are long gone. Though we've seen a resurgence of the center position in the last few years after the position was diminished due to small-ball lineups, teams have realized the value of rim protection.
With more ball-handlers came more penetration, and the lack of rim-protectors was hurting defenses. Teams therefore realized the value in guarding the basket, relying on big men who understand how to remain vertical without fouling.
But this hasn't meant more low-post scoring; today's centers are more concerned with pick-and-roll finishing and defense than any developed low-post game. Dwight Howard, Joakim Noah, Tyson Chandler and Roy Hibbert—four of the league's best centers—do not feature extremely dangerous post games. In fact, only Hibbert and Howard are even capable with their backs to the basket, but they're certainly not centerpieces of an offense.
As detailed through his offensive rating, Perkins hurts the Thunder most on offense. Though he is certainly an effective screener, teams do not need to account for him anywhere in the half court.
Take this pick-and-roll he runs with Durant earlier in the season against the Portland Trail Blazers. As Perkins catches the ball, he's in prime position to finish. All it requires is a bit of finesse, but he has the ball in the restricted area with an opportunity to put points on the board.
Robin Lopez, instead of accounting for Perkins, steps forward to double Durant. While this would likely be the choice given any other roller as well, it's hard not to notice how wide open Perkins is.
What makes this play truly stand out is the Trail Blazers' weak-side defense. C.J. McCollum doesn't even bother pinching into the paint to guard a totally free player only feet from the rim. Instead, he chooses to stick with Jeremy Lamb on the three-point line.
If Durant were to throw this pass, it would be extremely awkward and difficult. Yet McCollum chooses to take that away, leaving Perkins to do what he wants on the play.
Because Durant is a relatively unselfish basketball player, he makes the right play and finds Perkins. With Lopez lifted and Perkins already diving, Perkins has the advantage.
According to Synergy Sports (subscription required), however, Perkins finishes at the rim only 48.9 percent of the time. That puts him in the 23rd percentile in the league, or in other words, the bottom quarter of the NBA.
It should come as no surprise, then, that Perkins misses the bunny.
On the whole, even the Thunder regard Perkins as a no-pass zone. Check out this pick-and-roll with Miami, in which Durant hits a popping Ibaka. As Chris Bosh leaves Perkins to properly rotate over, Miami's Dwyane Wade does not get on the basket side of Perkins.
This allows an easy seal, with Perkins right underneath the rim.
Ibaka does not even consider giving the ball up to Perkins, who continues to stand there, in perfect position for a dunk. Maybe Ibaka doesn't see him. Maybe he can't find the right passing angle.
Both of these scenarios are unlikely, as Ibaka is staring right at the basket, and therefore at Perkins. It's likely a matter of trust, and Ibaka probably makes the smart decision in taking it himself.
The odds of Perkins both making a clean catch and finishing the layup aren't good. And if Wade fouls Perkins, that brings an entirely new set of problems for Perk at the free-throw line.
With Perkins out of the lineup, Steven Adams has taken over the starting center role. Clearly this indicates head coach Scott Brooks' desire to at least begin the game with two-big lineups, and so we can likely expect Perkins back in his starting role once he returns from injury.
It also won't impact Westbrook and Durant's production much, with Adams likely taking a backseat offensively and only playing spot minutes throughout the game. Not to mention that the lineup structure is the same: Ibaka still at power forward instead of center, and Durant at small forward instead of power forward.
But the brief period of starting should help Adams' development, as he's likely to take over the starting role once Perkins' contract comes off the books.
Much has been made of Perkins' diminishing skills and the Thunder's need to keep him off the floor. The latter is certainly true, but the former is probably an unfair characterization of what has happened to a once-respected post defender.
Players in their late 20s simply don't fall of a cliff like Perkins supposedly has. A more rational explanation considers circumstance, and that the aspect of Perkins' game that is most effective (post defense) is no longer an important part of basketball.
He has always been a zero offensively; but now that his defense is worth very little, the style of today's NBA has simply passed Perkins by.