On Monday, NFL icon Peyton Manning announced his retirement from professional football. He leaves behind a legacy that few current NFL players even have a chance at matching. Manning owns the records for passing yards and touchdowns; he has claimed five MVP awards, two Super Bowls, and was crowned the MVP of Super Bowl XLI.

But that didn’t stop Steelers running back DeAngelo Williams from questioning the future Hall of Famer’s effectiveness in his final season.

Williams took to twitter early Monday morning in response to Pete Prisco’s (CBS Sports) tweet that suggested the nearly 40-year-old QB still had it:

Williams, a fiery competitor not afraid to speak his mind, responded without pulling any punches:

It would be easy to chalk these tweets up to a case of sour grapes; Williams was sidelined as the Steelers fell to the Broncos in the AFC Divisional round.

But the feisty ball carrier, especially with the first tweet, highlights how many sports personalities have changed their tune regarding Manning over the course of the season.

When Manning’s foot injury in early November threatened to end his career before a final shot at glory, the Indianapolis Star crafted a piece debating if Manning’s career was over or not. Even in Indianapolis, where Manning is just as revered as he is in Denver, both contributors said Manning’s career was done.

It’s understandable why Williams has blown the whistle on the Media. The NFL offseason is full of the hopes and promises of the optimistic variety. Its the perfect time to play the “what if” game. But once the regular season starts, players better perform, or as Al Davis said, “Just win, baby.”

By all accounts, this was not a very Peyton-esque season. Two years removed from basically rewriting the record book for a passing in a single season, Manning tossed 9 touchdowns and 17 INTs. In the Playoffs, he combined for 539 yards over three games. He threw for 479 in a single game against the Arizona Cardinals in 2014.  There is no question his effectiveness was diminishing, and Williams isn’t wrong for pointing it out.

Williams, who admitted to feeling extra petty the night before the exchange above, smartly balanced his criticism by giving credit where credit is due, calling Manning’s career “astonishing,” emphasizing his emphasis on Manning’s performance this season.

But the fact remains; Manning became only the second quarterback to win the Super Bowl in the final game of his career. The first? John Elway. That’s pretty good company.

Williams, meanwhile, is still awaiting his first conference championship game appearance.