Really good sports movies from my perspective:
Agree on Mystery, Alaska. That's lots of fun.
Miracle was really well done, capturing hockey for people who aren't hockey fans.
Seabiscuit: yup, good movie.
Rocky. Not the sequels, which were popcorn blockbusters, but the original, which is truly a great movie.
Breaking Away
The Million Dollar Baby
Chariots of Fire
Bull Durham
(Full disclosure, I've never seen Raging Bull.)
And then a whole bunch more that are lots of fun, but probably not great movies, adding to the lists above:
Slap Shot (the king of hockey movies for hockey players)
Talladega Nights
Cars
The Natural
Happy Gilmore
Dodgeball
And then there are the documentaries:
A Sunday in Hell
Hoop Dreams
Do You Believe in Miracles
The Endless Summer