I'm an accountant so I'm going to do the math in a way that makes sense to me. Verbeek wants him to be a horse in the second half. Let's say that Carlsson is worth 1 point of value every game right now, whatever 1 point means to you - scoring, standings, or just an arbitrary hockey value indicator. If Carlsson plays 80 games at 1 point of value every game, he'd be worth 80 points for the whole season.
However, based on the analysis they've done, both of Carlsson as a player and rookie performance in general, they think playing him everyday will cause his value to decrease throughout the season. So in January, he'll be worth .9 points per game. February .8 points, March .7, April .6. So if Carlsson played 80 games, he wouldn't be worth 80 points. He'd be worth roughly 70 points.
But the Ducks think sitting him out will allow him to maintain his value better throughout the season, and maybe even increase it. If we're conservative and assume that this rest plan allows for even just a maintenance of his 1-point per game value, sitting him for 10 games doesn't decrease his value to the team. It keeps it at 70 points, the same as if they played him every night.
I'm not trying to prove that this is how they've calculated it or even that this is their exact thinking, so don't get caught up in the exact numbers. I'm just trying to posit a theory. But Verbeek has specifically mentioned the second half of THIS season. They've also talked about this being the plan for two months, not necessarily the whole year. Clearly they're not punting on the season entirely. They want Carlsson to provide as much value as possible for later games this season, and it's possible he can provide as much total value to the team under this plan as he would have by playing every game.