I wasn't sure why Marino was retiring now, but I guess he never filed his retirement papers with the league. This provided an opportunity for him and guys like Larry Little and Bob Griese to sign 1 day contracts with the Dolphins and officially "retire." It's a nice story.
As far as his place in history, Marino has to be considered one of the top QBs ever in the NFL. His 5000 yards passing in 1984 still ranks as #7 in
single season passing performances and is the only one in the top 20 that didn't happen in the 2000s. Additionally, Miami's passing offense was in the top 4 in the league from 1984 to 1995, 5 times as #1. Marino's numbers also have to be viewed in the context of when he played. From 1984 to 1999, you would see an average of 2 or 3 teams a season with more than 4000 yards passing. Over the last 3 years, 12 or 13 teams passed for that many yards. Marino was putting up those kind of numbers at a time when teams were built with the idea that they needed a good running game to complement the passing attack.
I understand the knocks against Marino, also. In 1984, the Dolphins lost the SB and then followed that up with a loss in the AFCCG. Then they missed the playoffs for 4 straight seasons and 5 of the next 6. Marino also didn't play with a 1000 yard rusher until 1996. Was it his ego that prevented Miami from committing more to the ground game at the expense of the passing attack? I don't know. I would think that a HOF coach like Shula would have looked at that stretch without a playoff appearance and realized that either the defense had to get better or the running game did. Marino could put up passing yards, but that wasn't enough. I don't know why neither of those things happened. Maybe it was a combination of Shula losing his touch, bad luck and bad drafting.