Mahomes has faced better defenses in the Super Bowl than Brady ever did. The best defense Brady faced was the 2014 Seahawks, which was no where near as great as the 2013 Seahawks due to injuries. And Timmy threw 2 picks in that game. Again, you keep comparing Brady's entire career to Mahomes' 5 years as starter. Let's see where Mahomes is at in 15 years. So far so good.
TB 12
St. Louis: Ranked 3 in yards, 7 in points (#9 in sacks) Win
Carolina: Ranked 8 in yards, 10 in points (#7 in sacks) Win
Philly: Ranked 10 in yards, 2 in points (#2 in sacks) Win
Giants: Ranked 7 in yards, 17 in points (#1 in sacks) Loss
Giants 2: Ranked 6 in yards, 25 in points (#4 in sacks) Loss
Seahawks: Ranked 1 in yards, 1 in points (#20 in sacks) Win
Falcons: Ranked 25 in yards, 27 in points (#18 in sacks) Win
Philly 2: Ranked 4 in yards, 4 in points (#16 in sacks) Loss (threw for 500 yards)
LA: Ranked 19 in yards, 20 in points (#15 in sacks) Win
KC: Ranked 16 in yards, 10 in points (#19 in sacks) Win
Kermit
SF: 2 in yards, 8 in points (#6 in sacks) Win
TB: 6 in yards, 8 in points (#5 in sacks) Loss (no TDs)
Philly: 3 in yards, 8 in points (#1 in sacks) Win (It's odd that they were unable to get any pressure in the SB... )
TB 12 INT % in SB = 1.4
Kermit INT % in SB = 3.4
TB 12 Win % in SB: 70
Kermit Win % in SB: 66.7