Dan Marino's career playoff stats (courtesy of wikipedia):
8 Wins (ergo, 10 losses)
56.0 Completion percentage
6.6 Yards per attempt
77.1 passer rating
15 rushing attempts
1 total rushing yard
0.07 yards per rush
1 rushing TD.
So Dan Marino was a below-.500 playoff QB and his rating was 77.1. Tarvaris Jackson's career rating as an NFL QB? 76.4. So come playoff time, Marino was barely better than T-Jack.
Apologists for Marino claim he was hampered by the fact that he played with a poor defense. That would not explain his 77.4 T-Jackish rating. But let's examine this claim versus, say, Jim Kelly who led the Bills to 4 Super Bowls. As one commenter noted on pro-football-reference.com:
The Bills and Dolphins each split their Reg. season games in '90, '92, and '95, yet Kelly and the Bills beat Marino and the Dolphins ALL 3 YEARS in the PLAYOFFS. The icing on the cake---the Dolphins had the HIGHER RANKED DEFENSE in both '90 and '92. Plus, Kelly led the Bills to the S.B. in both years. One other thing--Kelly also led them to the S.B. in '91 and '93 and his Defense in both of those years was ranked 27th out of 28 Teams.
Look at 1991 and 1993 -- Bills defense was next to last in the league http://www.pro-football-reference.com/teams/buf/ and yet they reached the Super Bowl.
When Marino was backed by a defense ranked 24th or worse, he made the playoffs....................................once. http://www.pro-football-reference.com/teams/mia/ In 1997 the Dolphins had the #26 ranked defense, eked into the playoffs at 9-7 and then proceeded to lose to New England. Well, I am sure the score was 54-51 or something, right? Well, no. Try 17-3. Marino's line? 17 for 42 with 0 TDs and 2 picks. Scored no touchdowns.
To further refute the ridiculous claim that Marino was victimized in the playoffs by his team's defense, let's look at the number of points he managed to put up in his 10 playoff losses:
20, 16, 14, 34, 10, 21, 22, 3, 3, 7.
You are not going to win many playoff games scoring an average of 15 points. If you remove the high and the low (34 and 3) you end up with 113 points in 8 games -- 14 points a game, even worse.
Much like A-Rod, Dan Marino was a far better regular season player and well, let's face it, a pretty T-Jackian playoff performer. When his team lost, it was generally because Dan failed to put up many points.
Does he belong in the Hall of Fame? Sure, just like someone like Rafael Palmeiro (steroids aside) belongs in the Hall due to very good regular season play over a very long period of time.
(You need to sort of ignore the fact that Marino had a Hall of Fame coach, came to a playoff team when he was drafted and yet made the playoffs only 10 of 17 years (59%) -- Troy Aikman came to a 3-13 team and yet made the playoffs 8 of 12 years (67%); and Jim Kelly came to a team that had been 2-14 and then made the playoffs 7 out of 11 years (64%)).
But is Dan Marino one of the most overrated players in NFL history? Yes. No doubt.