Mike Mussina's case, for the Hall of Fame, is an interesting one to me, because there are a lot a parallels with our own Mark Buehrle.
He was never the best pitcher baseball, but he was good for a long period of time. With 270 wins, he's 56 ahead of Buehrle. He didn't have 14 straight seasons of 200 innings, but he did have 9 straight. And he did have 11 seasons of 200 innings. He was thought of as a good defensive player, winning 7 Gold Gloves, Mark won 4.
Mussina had a very good 18 year career, getting double digit wins in every season except his rookie year, so that's 17 years of double digit wins. Buehrle had 15 years of double digit wins.
Mussina never won a Cy Young, he finished 2nd in voting once and finished 4th through 6th 8 times. Buehrle only received Cy Young votes once, finishing 4th. He was an All-Star 5 times, including the rather famous time that Cito didn't bring him into the game in Baltimore. Buehrle was an All-Star 5 times as well.
It seems to me that Mussina has a stronger case for the Hall, if Buehrle retires after this season, unless you give a lot of weight to the 15 straight seasons of 200 innings.