I don't know if he is that player, but if he were, yes it's a piece that's missing. On the other hand he could just have hit a purple patch of grittiness against rather ordinary attacks. Remember the Manicas sat out the first round when teams were at full strength.
I remember that Forster suffered a terrible loss of form (and supposedly confidence) after he last played for the national side. After his move to the Manicas his form has again picked up, that is true, but even in that line-up he has often cast a rather low-key figure. As a Goats' fan I can't remember many match winning knocks, nothing that really caught the eye. But you could always depend on him to grind out a 40 or a 60 and keep the best tail in franchise cricket company.
That said, I think he was treated rather unfairly when his international career was cut short after his only Test match. He had played two series against BD and NZ in 2011 where he didn't look dashing, not really like an ideal ODI player, but sort of gritty. He had a fifty against NZ and a couple of starts against BD, but averaged only in the low twenties (his ODI average is propped up by three fifties against Kenya). But nothing to suggest that he should be discarded for good after his next match. I believe we were talking about whether his game's not better suited to FC/Test cricket at the time. And then came the disastrous Test match in NZ where he batted at three--virtually opening (coming in in the third and first over respectively)--and he had scores of 6 and 18: but BT scored 11 runs in the match, Taibu 6, Hami 0 (opening after Vusi had jumped ship, which got Forster into the side in the first place), Tino 4, and Waller 23. To be dropped for good after that tour was harsh, but he didn't go home and score tons of runs in domestic cricket afterwards either.