UPDATE: The Wizards just said the injury is a "dislocated middle finger."
The official reason is because of a jammed/dislocated left middle finger that swelled enough to hold him out. Flip Saunders said Arenas suffered the injury "about two, three weeks ago" and got hit again yesterday on the finger, which caused the swelling. However, Saunders said the injury wasn't serious and holding Arenas out was more for precautionary reasons.
"If we had a game, he'd play," Saunders said. "There's no need to force that issue."
Arenas was indeed seen getting taped up on the sidelines while the scrimmage was going on, so yes, he does have a finger injury. That much is certainly true, and the Wizards are supposed to send an update officially classifying the injury.
After the scrimmage was over, the players each shot free throws to determine how many sprints they'd have to do. Despite making both of his shots -- meaning he didn't have to sprint -- Arenas did do some jogging while the others were sprinting full-on. It definitely appeared like he was running a bit gingerly on his left knee, the same one on which he had all the surgeries.
When asked about whether Arenas had any knee soreness, Saunders quickly said Arenas' knee was fine.
"No, no, no," Saunders said. "Everything else is fine. He ran sprints at the end, so he's had no problems [with the knee]."
Arenas himself declined to comment, telling Mike Jones that "I'm not talking. I'll see you guys media day of next year."
Now, before everyone goes crazy, this is probably nothing. None of Michael Lee, Jones and I noticed Gil putting any ice on his knee, and Arenas was bouncing around a bit while he was engaging in a post-practice shooting contest with Randy Foye. (In case you want to know who won, Foye said he wouldn't disclose that). Arenas had also been sitting down for a while, so maybe he was just trying to get loose. But given the history, anything that happens with Arenas' knee is newsworthy, so I figured I'd pass it along.
Other stuff coming later...