Old Guy Tying New Stroke? Beware!

OK, so I'm not Michael Phelps.  But I do have a bit of his ego and I thought maybe I could try his freestyle stroke.  No, not the one on the TV commercial where he plows through pavement.  That's for the younger crowd.  I'm talking plain old throw yourself up with each stroke like the a butterfly to get more reach and more body whip with each kick.  Where did I land?  On the couch for two days - unable to move.  I learned my lesson, or so I thought.  That was a year or more ago.  But yesterday, I recalled a recent reply to that post where I first pointed out MP's freestyle leap.  That reply suggested opening one's fingers to make the water slide through faster.  Sounds logical (after you get past the part about giving up on cupping the water to get more pull).  Well I tried it.  Naturally, my arms came through the water faster - so did my elbow and almost instant tennis elbow pain that throbbed until I was about 3/4ths through my workout.  So as for radical new stroke technique?  It doesn't look good for moi.  I guess I'm stuck in the slow lane with the guy in the waterproof leg cast.