To stick to critiquing ideas, I think that:-
In my opinion, Wallace was a player who never really turned up.
He was all around the ground for 5 years and led our LV team to cup victory - he won more than a few man-of-the-match awards and was often mentioned by many commentators with high praise, so I think your assertion that he "never really turned up" is incorrect.
An “out & out seven”, who spent half the game nowhere near the breakdown.
He tackled and poached away and won many turnovers - I think part of your thinking here possibly relates to the evident coaching decision to have him lurk occasionally on the wing and partly because you couldn't see him as he was in the thick of it under a ruck.
...but for me was way too inconsistent to hold down a first team jersey at Quins or any other Prem side.
For 5 years (2011-16) he was holding his place at Quins easily (7 tries in 2015/6) but, like much of the team, suffered under the later COS and Kingston years (2014-present) as most of the team ran around clueless at times. Following his injury, his form did drop (but, for example, his tackle completion was 92/94% for the last two season) and he has been shunted sideways with the advent of Clifford and Chisholm. He played for Saxons and for a non-capped England game.