The Detroit Pistons’ rough season has taken another turn for the worse.Point guard Derrick Rose has been diagnosed with a Grade 2 ankle sprain. He’ll undergo treatment and be reevaluated in two weeks but it’s likely that Rose won’t play again this season.Lottery-bound Detroit has 20 games remaining, beginning with a home game against Oklahoma City on Wednesday.”It’s very disappointing, more for Derrick than anything else because the young man has been through so much with his body,” coach Dwane Casey said.Rose has dealt with a variety of injuries in recent seasons but has been the Pistons’ best player this season. He’s averaging 18.1 points and 5.6 assists in 26.0 minutes per game while appearing in 50 games. Rose was injured during the first half at Sacramento on Sunday, when the Pistons endured their eighth loss in their last nine games.Rose signed a two-year, $15 million contract as a free agent last summer. He has not appeared in more than 66 games in any of the last eight seasons.”It’s very tough, but he’s a strong guy,” guard Brandon Knight said. “Even speaking to him after the injury, he’s strong and he’s going to be back fine. He’s an inspiration to us all.”Knight is now the team’s starting point guard.He was behind Reggie Jackson and Rose on the depth chart after Cleveland traded him to Detroit last month. Jackson was bought out of his contract last month and joined the Los Angeles Clippers. With Rose sidelined, Knight is the most experienced point guard on the roster, though he’s dealing with a quad injury.”That’s basketball,” he said. “Every place I’ve been, things change quickly. You’ve just got to be prepared and dive in and do the best you can. It’s been fun thus far.”Knight has averaged 16 points and five assists over the last four games.