If the Designated Player Rule is the Beckham Rule you could say that the Homegrown Player Rule is the Tristan Bowen Rule. The league's first ever HGP played for the Galaxy, Fort Lauderdale, Chivas USA (also their Reserves), SV Roeselare and Seattle Sounders FC (and Reserves). He is now going to be with the young New England Revolution where he can hope for less injury troubles and more than 566 minutes for all versions of the Sounders.
Bowen is best as a wide midfielder who cuts in to create scoring opportunities for himself or to pass to another. Lacks the crossing of a traditional winger. Not dangerous on set-pieces. Could be a bit quicker on the shot. Has a developing first touch. Can use his speed out wide.
Bowen is an aggressive on-man defender, but maybe in a bad way. Not great at occupying dangerous spaces, he's much more of an attacking man. Should not be a key man in defending stoppage plays.
He's big enough, but his key is speed. Can breakaway from most MLS defenders. Will generally avoid contact.
Best Case 2015:
Now with the New England Revolution he is in a system built with several others that play his style. Heaps has shown that he can develop those players into useful cogs. Should be able to get significant time in the 18 on a good team.