Stagnation is the name of the game with sports titles - I mean, the sport doesn't change, so what can you expect? Save for those ridiculously quirky ones, I tend to ditch sports games like the plague.
Mega Man has the same problem Sonic does - it's the spam conundrum. Let's not kid ourselves: every Zelda and Halo game (using both to avoid the 'lulz u r fanboy' accusation) since their 3D debut has been the same. Either you are green-tunicked dude on quest for sword or generic space marine in space with more different laser weapons. The difference is, these games are released rarely. In six years (from 2001), Halo has had 3 games (Halo, and Haloes 2, 3), and LoZ 2 (WW and Twilight Princess). How many Mega Mans have been released in that time?...Too lazy to count, but a lot more than 2.
http://en.wikipedia.org/wiki/List_of_Mega_Man_games
There. Count if you want.
Likewise, Sonic got burned by two bum games post Sonic Adventure 2 Battle (DX and Sonic Heroes) and then the spam on this gen.
The moral is this: you can throw me the same game with a few upgrades if you don't do it very often, and if the game is still solid inside. Once you start spamming, you reduce the series to a paltry remnant of what it was.