Odell Beckham Jr. -- Spikes Gronk ... Wins Madden Cover -

Odell Beckham Jr. just made the biggest catch of the NFL off-season ... snatching the "Madden 16" cover right out of the hands of fellow finalist Rob Gronkowski.

Beckham Jr. and Gronk beat out a bunch of other NFL studs ... like the Cardinals' Patrick Peterson and Steelers wideout Antonio Brown ... to become the last two dudes standing on Madden island.

Fan votes determined the final winner, and Odell took it home with a super narrow 52.5% of the votes -- but arguably Gronk is the real winner here.

There's a little thing known as the Madden curse ... and the Giants star is now susceptible to the same fate suffered by Garrison Hearst, Peyton Hillis, Shaun Alexander, Vince Young, and bunch more.

Even last year's cover guy -- Richard Sherman ... jacked up his elbow and lost the Super Bowl.

Ummm ... congrats, Odell?

We asked Giants co-owner Steve Tisch last week about OBJ possibly getting the honor (?) -- he was less than thrilled.