Would have loved to see this system employed with Joevin now and Carlos in his prime as the wingbacks, but alas if wishes were horses...
Joevin WAS used as a wingback under Hart
Problem was.....he hardly ever used to track back
And to those who say he does it for his club......he doesn't track back that much. When he plays wing back for Seattle....he's more of a stay at home defender. Now...that limits his effectiveness going forward but Seattle has enough quality in the attacking third to overcome that.
Later in the season....Seattle began using Joevin in the same way that Hart was using him for the national team...as a wide sided left midfielder.
In the MLS final....Joevin hardly overlapped. His role was clearly defined i.e. stay at home....and essentially Seattle used the THREAT of Joevin going forward as a counter to Toronto FC's own wide players taking too many liberties going down his side.
At the end of the day....it comes down to 2 things:
Personnel.....T&T has relatively fewer attacking options if JJ plays as wing back which puts more pressure on midfield and defence, compared to Seattle.
JJ's willingness to fully perform the role for club vs country
Something to bear in mid....he was damned well effective in that "higher up the pitch" role for T&T against Guatemala. Without that, we wouldn't be in the Hex.