Beasley set his personal worst playing for Phoenix. Heck there are years when he was only 10 or 15 percent below average.
Ehh... not really. He's been consistently terrible. He's had a couple years since his return from China where he merely "stunk", but in virtually any season where he was granted enough playing time he was one of the most detrimental players to his own team in the league.
There isn't a single year in his career where his team was not wildly more successful with him on the bench. His most "efficient" season came for Houston in 2015/16, while his individual stats gave the appearance of someone who wasn't a disaster, the Rockets were outscored by 10.5 points per 100 when he played and posted a +1.3 when he didn't. So, even at his best, when it comes to helping his team win, he is one of the worst players... ever.
He's a dude whom if the entire league subscribed to "moneyball" roster building would have been out of the league back in about... 2011.