The NBA has seen many stars who have either exceeded expectations or failed to meet them. From NBA Draft busts to devastating injuries, the league has seen many players rise to the top only to slowly fade away at a certain point in their careers. Here, we take a look at a list of five NBA stars who have underperformed during the 2020-21 season. 5 NBA stars who have underperformed this season1. Kemba WalkerKemba Walker #8 of the Boston Celtics looks on during the game against the LA ClippersKemba Walker has taken a big step back since coming off his knee injury.The starting point guard just doesn't seem the same and is averaging just 15.0 points and 4.3 assists per game this NBA season. He sometimes goes for odd FG ratios during stretches of a game, and this has made fans question whether he's 100% healthy. Here's what Boston Celtics head coach Brad Stevens had to say regarding Walker's play before the team's win against the Raptors on Thursday night:"Nobody is putting more pressure on himself than Kemba but we can all do better for him"Brad Stevens spoke with @Scalabrine about Kemba Walker's struggles this season pic.twitter.com/7WEV2Ho7fI— Celtics on NBC Sports Boston (@NBCSCeltics) February 11, 20212. Russell WestbrookRussell Westbrook #4 of the Washington Wizards reacts after a playRussell Westbrook seems to have regressed since joining the Washington Wizards.When John Wall was traded for Russell Westbrook at the start of the NBA season, many believed that the Wizards got the better end of the deal.However, the Washington Wizards still have one of the worst records in the league, and most of their wins came when Westbrook wasn't playing.Wizards this season:4-3 without Russell Westbrook2-13 with Russell estbrook pic.twitter.com/KWf2XCdcvz— StatMuse (@statmuse) February 11, 2021Westbrook's turnover issues have grown even more since joining Bradley Beal on the Wizards squad. The 32-year-old was shooting 38% from the field a couple of weeks ago. He is now averaging 41.6% from the field and 34.3% from three. The former NBA MVP is not playing MVP basketball and doesn't look like the same impactful player that we're used to seeing.