After the 49ers finished off their latest romp -- 28-16 over division rival Seattle -- Williams scoffed at the notion that Purdy is propped up by the offense.
"I don't get why people say he's a system quarterback," Williams said via 49ers Web Zone. "... No system quarterback makes tight-window throws before they're there, throwing people open, putting the ball into a window and trusting his receiver to get there, layering balls over linebackers who are in good position, and still getting the ball over their head, getting it to the playmaker.
"(He's) just so accurate. You watch a lot of his throws, the accuracy gives them guys a chance to run after the catch, and I don't think he gets enough credit for that."
On Sunday, Purdy tossed for a career-high 368 yards with two touchdown passes and one interception. His 122.1 passer rating was his 12th career game with a 100-plus rating, second-most all-time in a player's first 18 starts since 1950, tying Dan Marino and Kurt Warner, behind only Patrick Mahomes (14).
With a 70.4 completion percentage, Purdy became the fourth QB in the Super Bowl era to have a 70-plus completion percentage in seven straight games within a season (joining Joe Montana, Drew Brees and Sam Bradford).
"In locker rooms, guys who know football, guys who study us before they play us, there's no way you can look at him and say, 'That's a system quarterback,' when you watch the throws he makes, you watch him making them under pressure," Williams said. "I mean, he rarely checks the ball down. Everything is going upfield, getting the ball upfield. He even has the ability to buy extra time with his feet. And even when he does, his eyes stay down the field. Very seldom is he looking to run the ball past the line of scrimmage. He really wants to get it into his playmakers' hands.
"I think he does the best job right now in the NFL at getting that ball into his playmaking hands, whether it's five yards down the field or 55 yards down the field. He can make every throw. He literally can make every throw, and you can't show a throw that he can't make."
Williams believes Purdy's standing as the final pick of the 2022 NFL Draft has naysayers clinging to their evaluations.
"I know obviously with him being the Mr. Irrelevant, everybody is slow to give him his flowers because then what's that say about a lot of scouting departments if you let a guy like this slip to Mr. Irrelevant pick," Williams said. "I think a lot of people are slow to give him his props just because of his draft status and where he was drafted. If he was Zach Wilson, I think he'd probably be unanimous MVP, the next coming of Aaron Rodgers or somebody like that. But since he's a Mr. Irrelevant pick, and this is what, almost two years of him putting just unbelievable quarterback play on film and it's still guys saying, 'Hey, I think it's Deebo. I think it's Trent.' I think, yeah, that's not realistic."
For Williams, Purdy's play heightens the offense, not the other way around.
"His success is not a secret, and it damn sure ain't got nothing to do with the system."