The Detroit Pistons have been one of the most surprising teams in the NBA this season and the Milwaukee Bucks have one of the most disappointing, which is an almost exact reversal of the situation a year ago, when the Pistons were one of the league’s most dysfunctional teams while the Bucks stunned everyone with an unlikely playoff push. There’s more to the rise of the Pistons and the fall of the Bucks than Greg Monroe - whom Detroit let walk for nothing in the off-season and whom Milwaukee won a bidding war to give him a max contract - but it certainly doesn’t look good.

Monroe has always put up good individual numbers but he’s now in his sixth season in the league and he has never played on a team with a winning record. It would be easy to blame that on the terrible situation he was drafted into in Detroit except there’s no way the Pistons would have the modest amount of success they are having this season with Stan Van Gundy’s four-out system if Monroe was still there. Monroe can’t guard on the perimeter or protect the rim, he needs the ball in his hands and he can’t stretch the floor or open up the paint for anyone else.

It’s very hard to build a team around a guy with his skill-set in the modern NBA. He doesn’t have the shooting ability to spot up off a pick-and-roll or the athleticism to be a rim-runner so any team that plays him big minutes has to play a more traditional offense based around holding the ball and entering it into the post. The problem is that bigger and slower teams have to be able to play elite interior defense to keep up with smaller and faster ones and Monroe has neither the physical ability nor the inclination to be a defensive anchor.  

The only way to make it work would be to pair Monroe with a shot-blocking presence who can move his feet and who can shoot 3’s and open up the floor for him to work in the post on offense. Of course, guys like that are worth their weight in gold and Serge Ibaka, Anthony Davis, Karl Towns and Kristaps Porzingis aren’t walking through that door in Milwaukee. Even if you one of them, would forcing them to fit their game around Monroe really be the best use of their skill-set?

A generation ago, it would have been a lot easier to build a good team around Monroe. Most teams played through the post and big men weren’t required to defend out in space as much while the illegal defense rule forced defenders to stay close to their men and prevented them from packing the paint. Those types of defenses Monroe in a double-bind - they make him less effective on the ball because of all the attention he draws and a less effective off the ball because no one has to guard him.

The way the league is going, there’s a whole breed of players - wide-bodied and slow-footed big men who can score at a high level with their back to the basket but can’t shoot 3’s and can’t move their feet on defense - who have suddenly become far less effective than they would have been in a previous era. Guys like Monroe are literally becoming dinosaurs and it will be interesting to see if any of them can be a featured player on a good team in the pace-and-space era of NBA basketball.

Pau Gasol: Gasol wouldn’t have been on this list five years ago when he was one of the better defensive big men in the league but age has really impacted his foot speed and he doesn’t have the same physical tools as when he was winning two titles with the LA Lakers. The Bulls had to bench Joakim Noah and Nikola Mirotic in order to make Pau more comfortable on the floor and they appear to have boxed themselves into being a fairly average team with him as the featured player upfront.

Al Jefferson: Jefferson has been the anchor of a fairly modest revival in Charlotte that has resulted in one playoff sweep at the hands of the Miami Heat in 2014. He’s posting better numbers in their new more wide-open offensive system but his impact on the Hornets offense is negligible (105.5 offensive rating with him on the floor vs. 105.4 off it) and the defense is much better without him (105.9 defensive rating with him and 100.3 without him). More importantly, Charlotte has invested high lottery picks in Tyler Zeller and Frank Kaminsky and there’s no way to maximize them with Jefferson taking up so many minutes in the post.

Brook Lopez: The Nets have no choice but to build around Lopez considering how unattractive they will be to potential free agents and their dearth of draft picks over the next few years. Lopez is improving as an interior defender and he has always been able to shoot 20+ foot jumpers but it still remains to be seen how good a team can be in the modern NBA when they feature such a glacially slow big man on both ends of the floor.

Nik Pekovic: Injuries are the big question with Pekovic - he has never played a full season in five years in the NBA and he’s now on the wrong side of 30 and doesn’t appear close to returning to the court anytime soon. Even if he could play, though, there aren’t a lot of minutes for him in Minnesota thanks to the emergence of Karl Towns and Gorgui Dieng and there aren’t a lot of situations around the league that would make sense for a guy with his skill-set and his massive contract.

David Lee: Not many two-time All-Stars on a max contract have ever been humbled as badly as Lee, who had to watch the Golden State Warriors go from good team to one of the greatest of all-time as soon as they took him off the floor. He’s a living and breathing example of the small-ball revolution - even a big man with Lee’s prodigious scoring and passing skills can’t be very valuable if he can’t shoot or defend. He’s no longer a starting-caliber player and his -10.6 net rating means his hold on a rotation spot in Boston is precarious at best.

Lee is a perfect example of the problems that a team runs into when they feature a big man with his skill-set. The Warriors would not have won a title if he was still a starter and they might not have even gotten out of the first round - it’s probably not a coincidence than their playoff success began in 2013 when Lee went down with a hip injury in Game 1 of their first-round series. Taking Lee out of their rotation was like unclogging a drain as all of a sudden the Warriors could space the floor and defend in space, the two keys to their emergence as the best team in the league.

The struggles that all these guys are having should be a real concern to teams that have invested heavily in younger big men with the same skill-set, guys like Enes Kanter, Jahlil Okafor and Nik Vucevic. For as much skill and scoring ability those guys have, they better be in the gym working on their jumpers and their lateral quickness and they better commit themselves to being exceptional positional defenders. The modern NBA is all about space - being able to create it on offense and play in it on defense - and if you can’t do that it doesn’t matter what else you can do.