Even though the Denver Broncos paid tens of millions of dollars for Russell Wilson to get off of their roster, Warren Moon says he's convinced the quarterback isn't washed ... telling TMZ Sports this week there's "no question, Russell can be very effective."

Moon -- a former Seattle Seahawk who stayed close with the franchise in retirement -- has seen the majority of Wilson's career up close ... and he seems sure that despite what the 35-year-old signal-caller has put on tape these past two seasons in Denver, he's still got juice left.

Moon says, though, it will take surrounding him with talent -- and a good offensive scheme -- to bring that all out.

Of course, there aren't too many organizations with those traits who are looking for a quarterback at the moment. Most have franchise guys they like -- and the ones that don't appear poised to select one of the top QBs in next month's loaded draft.

Plus, guys like Kirk Cousins and Justin Fields look like they might be available for QB-needy teams as well.

But, Moon says he thinks Wilson will land on his feet somewhere ... it just might take a minute.

As for if he could see Wilson settling for a backup job in 2024 -- Moon said he doesn't think that's a possibility. He believes Wilson would just hold out until a starting job opened up -- similar to what Joe Flacco did with the Browns last season.

Former NFL executive Marc Ross also talked with us about Russ this week ... and he says he's not so sure he'd bet on Wilson getting a starting gig in '24.