Perceptions can play tricks. Sometimes, they're flat-out wrong.

Michael Crabtree demonstrated as much early during his tenure with the San Francisco 49ers. He came to the team with a reputation as a diva receiver, reinforced by his alliance with Deion Sanders. But the 2009 first-round draft choice quickly earned teammates' respect with his hard work and elevated football IQ.

Subsequent events have renewed questions about Crabtree. There was a fight with team leader Vernon Davis, apparent disinterest in the exhibition season and implied frustration with his role.

"All I do is run routes," Crabtree said following an overtime playoff defeat to the New York Giants last season. "When you don't get that many opportunities, it's hard to talk."

Asked specifically whether he had been open, Crabtree said, "Half the time you're not going to be open. That's why they call you a playmaker -- just give you chances."

A comment or two made in frustration should not define a player.

Yet, as much as I've resisted buying into perceptions on Crabtree, negative possibilities came to mind when considering his developing friendship with new teammate Randy Moss. Visions of the two talented wideouts growing close could foreshadow difficulties for opposing defenses -- and, possibly, for 49ers quarterback Alex Smith.

Alas, the New England Patriots traded Moss to Minnesota in 2010 partly because the veteran receiver had become too high-maintenance for quarterback Tom Brady. Crabtree has been around three seasons now, but he's still only 24 years old. I wonder to what degree Moss could impact him, for better or worse.

Again, perceptions can be unreliable. In this case, I found them inescapable.

Time is on the 49ers' side. Moss will earn no guaranteed money without first earning a spot on the 53-man roster. He might wind up being a terrific teammate and mentor even if that has not always been the case previously.