For much of this season, the defending champion Milwaukee Bucks have not seemed like the same Milwaukee Bucks team we had come to know over the past few seasons. Milwaukee won more than 71 percent of its regular-season games and led the league in wins (by a mile) during the first three years of the Mike Budenholzer era, but at the All-Star break of this season, the Bucks were just 36-24, good for the fifth-best record in the Eastern Conference.

Of course, it makes sense that the Bucks didn’t look like themselves until recently. Because until recently, well, they weren’t themselves. Each player in the team’s trio of stars (Giannis Antetokounmpo, Khris Middleton and Jrue Holiday) has missed double-digit games because of injury, rest or COVID-19 protocols, as have key reserves like Pat Connaughton, George Hill and Wesley Matthews. Donte DiVincenzo played only 17 of 56 games before he was traded to Sacramento. Most notably, though, the team did not have Brook Lopez, who appeared only in the season opener before being sidelined for nearly five months due to a back injury that eventually required surgery.

Without Lopez patrolling the paint, the Bucks had to make some dramatic changes to the defense that has been the backbone of this recent run of contention. Milwaukee still prioritized protecting the paint at the expense of leaving shooters open on the perimeter, but replacing Lopez in the lineup with his backup, Bobby Portis, necessitated shifts in pick-and-roll coverage strategies and help-defense alignment. The degree to which those shifts affected the team’s defensive performance makes it ultra-important that Lopez returned in time to ramp himself up for a playoff run.

Lopez is an expert in Budenholzer’s preferred “drop” coverage scheme, wherein he sinks back into the paint when his man sets a screen and the teammate defending the ball-handler fights over the top of the pick, so the duo can coax said ball-handler into the dead zone near the elbows or back half of the paint.⁵ From his perch near the restricted area, Lopez can both wall off the basket and, with his length, challenge a floater or short midrange shot. Very few players in the NBA are better than Lopez at executing drop coverage, and the Bucks turned his proficiency in that area into the foundation of their defense.

Portis, though, is not particularly good as a drop defender. Among 58 players who defended at least 1,000 ball screens with drop coverage from 2018-19 through 2020-21, Portis ranked 51^st in points allowed per possession, according to Second Spectrum. Portis does not have the same timing and/or defensive instincts as Lopez, which makes the dual responsibility of corralling the ball-handler and protecting the rim a bit more difficult for him.

Nevertheless, with Portis acting primarily as Lopez’s backup during the former’s first season in Milwaukee, Budenholzer had Portis play pick and rolls largely the same way his starter did — presumably to keep things simple for everyone else on the floor. With Portis starting and playing heavier minutes for most of this season, though, Budenholzer instead optimized his coverages to take advantage of the strengths Portis has that Lopez doesn’t — namely, his athleticism and ability to operate in space. Rather than sinking back on nearly every ball screen, Portis spent more time stepping up and attacking the ball-handler with a switch, blitz or show.

What worked for Portis did not necessarily work quite as well for the rest of the team, though. Milwaukee sits just 14^th in defensive rating this season,⁶ the team’s worst mark of the Budenholzer era. A lack of rim protection seems to be the primary culprit: While the Bucks still do not allow opponents to take very many shots at the rim, those shots have been converted at a significantly higher rate. The Bucks have allowed opponents to attempt between 21 and 24 percent of their shots within 3 feet of the rim during every season of Bud’s tenure, but after checking in second, first and seventh in field-goal percentage allowed on those shots in his first three years, they rank just 17^th this season.

Losing one of the league’s premier rim protectors will do that to a defense. Lopez ranked seventh (52.5 percent), fourth (46.7 percent) and third (49.3 percent) over the past three seasons in field-goal percentage allowed when within 5 feet of both the shooter and the rim,⁷ according to NBA Advanced Stats. He also challenged at least five shots per game in each of those seasons. Portis has challenged 4.1 shots per game this season, allowing a 56.8 percent conversion rate that ranks 26^th out of 98 qualified players. That’s not bad; it’s just not elite. Lopez is elite when he’s fully healthy and on his game.

As Antetokounmpo told ESPN’s Ros Gold-Onwude, “Brook makes the game so much easier on me and takes so much pressure off of me — especially on the defensive end of the ball. He’s so big, long and smart, it’s like he can guard the big and the guard at the same time; and that allows me to be more aggressive defensively.”

Since his return, that version of Lopez has been there, for the most part. The Bucks’ defense often looks like the platonic ideal of what Budenholzer would expect from Lopez and company.

There are some possessions, though, where Lopez doesn’t seem to trust that, in his current physical state, he can still make a late contest from deep in the paint, and he gets a little jumpy. He’ll come out a little bit higher on the floor than he probably should and get blown by, or challenge a driver that he should probably bait into a floater, and instead concede a wraparound pass to his man under the basket.

Of course, it’s not all that surprising that a 7-foot, 282-pound man is moving slower after a five-month absence for back surgery. But he’s still so big, so long, so smart that he gets away with moving creakily more often than not. Expert timing and trusting your body to do what your mind tells it to take a bit more time to recover than the body itself does. If the way he’s progressed is any indication, he’ll get there eventually.

Perhaps the most encouraging development for the Bucks was Lopez’s offensive performance on Tuesday night against the Bulls. In his first nine games post-injury, he mostly struggled to find a rhythm and really only produced from 3-point range. But on Tuesday, in what was clearly his best offensive game of the season, Lopez was considerably more involved in the action. He set 28 ball screens against the Bulls, according to Second Spectrum, the most he’s set in any game this year. He and Holiday, in particular, made mincemeat of Nikola Vučević in the pick and roll, and Lopez capitalized on his success early in the game by being much more aggressive later on.

Lopez is typically a complementary player within Milwaukee’s offense, with Antetokounmpo, Middleton and Holiday using the lion’s share of possessions. There are scenarios where the Bucks will need him to be more of a factor, though — like his 33-point clinic against the Atlanta Hawks in Game 5 of the Eastern Conference finals last year⁸ — and seeing that he has this type of game in him just a few weeks after getting back on the floor is an excellent sign.

Milwaukee can still turn to Portis if it needs more scoring from the center position, or just someone who will hunt more aggressively for a shot. Doing so would necessarily result in a defensive downgrade, though, which is almost surely why Lopez has resumed his place in the starting lineup even though Portis fared quite well in his absence. If Lopez can return to being a consistent offensive threat, Budenholzer won’t have to make much of an offense-defense choice during the playoffs. He’ll be able to dole out the minutes between his two centers as he sees fit, with each of them playing the role they were signed to play — the roles they played on the way to a title last season.

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