Warren Moon Warns Baltimore Ravens ... Don't Rest Starters In Week 18!!!

Warren Moon says if he were coaching the Ravens, he wouldn't sit Lamar Jackson, Odell Beckham Jr. or any other starter this week -- telling TMZ Sports he believes the moves could seriously ruin their chances at a Super Bowl.

Of course, with the No. 1 seed in the AFC already locked up, John Harbaugh revealed earlier this week Jackson and several others will take a seat on the bench against the Steelers on Saturday in order to stay healthy for the postseason.

Moon, though, doesn't think that idea's so great ... explaining that because Baltimore has a bye in the first round of the playoffs, there's now a far greater chance the squad will be rusty when it finally kicks off its divisional round…