i thought i recently saw a % of the "suprise" onside kick and it was recovered by the kicking team over 50% of the time.
the problem is, this year, this move seems to be more prevelant. thus, it loses the element of suprise that has made it so effective in the past. i believe the rest of the year it will be much less effective as im sure coaches are drilling the front line in the head to not get a head start running down the field until the ball is off.
but i have never seen it to start a game, so i dont think it was a bad time to try to make a play and snag momentum. it was a decision that didnt pay off. call it a gamble since field position is clearly huge in this game.