It's really easy to make fun of Andre Roberson for his shooting. There are plenty of clips of him air balling free throws, badly missing open 3-pointers, and showing why he's one of the NBA's worst floor spacers. In the era of pace and space, he's a sore thumb among a league full of amazing shooters.

Roberson is also one of the most important players on the Thunder and a huge part of their success this season. We can laugh at his missed free throws, but he more than makes up for it as one of the defenders in the league. Oklahoma City's identity is its defense. It's how OKC wins games and it's why the Thunder were able to turn their season around. 

Nobody is more important to that Thunder defense -- currently ranked fifth in the league in defensive efficiency -- than Roberson. Not only is his 10.0 net rating the highest on the team (among players that actually play significant minutes) but the defensive difference is insane. When he's on the floor, OKC only gives up 96.4 points per 100 possessions. When he's on the bench, that dramatically rises to 108.3 points per 100.

Nobody on defense, or offense, has as big of a difference on one end of the floor as Roberson. Which is why the potential season-ending injury he suffered Saturday night is absolutely devastating for the Thunder.

The Thunder didn't just lose a starter that provides length on the wing. They lost and aggressive defensive stalwart, who can guard the opposing team's best player. When Carmelo Anthony, Paul George and Russell Westbrook are on the floor without Roberson, they have a negative net rating and their offensive efficiency is only slightly better.

If there is an area where Roberson brings the Thunder down it's his offense, but the difference is too small to be worth the defensive drop. They score 107.3  points every 100 possessions when he's off the floor as opposed to the 106.4 when he's off of it. The big three of Anthony, George and Westbrook have an offensive efficiency of 111 when Roberson is off the floor and 108 when he's with them. So there is a dip there. But again, the defensive gains are outweighing the offensive loss, which is truly remarkable about Roberson.

In this era, players need to be floor spacers. They have to able to provide something on offense, otherwise defenses single them out and attack those weaknesses. Roberson has not only found a way to be such an effective defender that his offensive weaknesses are overshadowed, but at the same time, he's found a way to not be a train wreck offensively.

Players like Roberson are a rarity. There are others players in the league like Roberson that are strong enough defenders to maintain a rotation position. Bismack Biyombo turned his rim protection skills into a big pay day. Michael Kidd-Gilchrist is a big part of the Hornets and he has by far the weirdest looking jumper in the NBA, but his defense is elite. Tony Allen made an entire NBA career out of his defensive skills. However, an argument can be made that all of these players are still better players offensively than Roberson.

Yet, that hasn't stopped Roberson from being a more effective player. He puts himself in position to succeed on offense and gives the other team absolute hell on defense. Despite shooting 22 percent from 3-point range this season he is still not a liability. In today's era that is impressive.

The Thunder losing someone like Roberson will hurt. They can't just simply bring someone up off the bench to replace him, because his defense isn't easily replaceable. Oklahoma City is really going to be put to the test here. Let's see if it can maintain an elite defense without its best defender.