But you need to separate "Washington Mantha" from "Detroit Mantha".
If the trade return was based on just the former, then yes, the Wings should have gotten more. But Tony was never going to play for the Wings like he is currently playing for the Caps (in any sustained capacity, anyway).
Washington may have gotten a superb player. But that doesn't mean that Mantha would have played like that in this town with this roster.
Had Detroit kept him and he continued to look mediocre, how is that better use of assets?
But a players value is defined by his ability + his potential. So my point is his trade value should have been higher because mantha had the potential to do exactly what he is doing once traded to a good situation.
Why on earth would we ignore a players potential when assessing their trade value?