i can understand both sides here.
I understand Dartrebs point of view as a manager of his own team, yet i can't deny some of the logic that Joe mentioned. So here is what i see.
To me, Dartreb still has a chance to win the league. he's a game behind Mizu, and considering that the red conference is pretty deep, a game often means nothing. i haven't analyzed the schedules extensively, but to me, he still had a shot. However, looking at his team, he has an aging team and would require to rebuild at some point. Claeys 33y old, Vaes 32y old, they are close to start there decline. if Dartreb doesn't have a deep financial reserve, then this was the time to hit the rebuild button. he's safe from relegation, so he has a 1.5 seasons to tank up cash. So i understand his decision, and considereing the timing, he could have had some more merchandise and had he waited a week or 2 more, he would probably have earned more because teams then gear up for the PO's.
From a NT point of view, you need to try and win the maximum of the games, this to give the owners of the players a max amount of revenue. they keep the players in good shape, you need to do your best to repay them for it. However, i'll look at the timing again. Belgium is facing Suomi, a team that isn't likely to be beaten. should they have bad GS, they could CT to make it to the next round (to be sure of making it to the next round). Belgium is already qualified, so no worries there.
However, in the next round, we face the best teams, with a chance of going to the world championships. Does the Belgian Nt stand a chance? it's a small one, but a chance none the less. So again, i look at the timing. Should Dartreb have kept his players longer, then he would have had to sell them in the middle of the competitive games, there GS costing us 2 or 3 important games and without a doubt that would nearly eliminate us from going to the world championship. However, by selling them now, he'll have a poor GS for Suomi, a poor GS for the first next game (pray that we face slovenko in the first game, cause they play home so that would have been a lost cause anyhow) and maybe for the second game too. However, if he had to sell them, then this was probably the best timing without hurting the NT to much (it would have hurt regardless of how you looked at it!)
So fom where i'm standing, Dartreb made the best decision for the NT. As for his own team, i think i would have held them on for a bitt longer, to get the merchandise but also to get a better feeling for the PO's. Dartreb has all the hard opponents in home games (except the cowboys) so to me, he could have ended first. The game with Mizu would have been the point where he'd have to make a decision if he was all in for the championship or not. considering he had a good chance and that the championship gives you a huge revenue boost, i think that for that and that decision alone, his timing from a teamowner view was a poor one.
but in terms of the NT, if he had to sell, then that was the timing that it would hurt the NT the least (ofcourse, i'm considering that those who bought Claeys & Vaes will maintain there GS.... should they fail to do so, then Belgium will have 5 more games and just crash out into the consolation tournament.
So for Dartrebs:
in terms of managing your own team, i would not have sold them yet and there, i would argue you made a mistake ( and i have to agree with Joe for a couple of his arguements). However, from a NT perspective, you took the least bad decision (there is no good decision here except to hold on to them till the new season, but then there value will drop even more).
please note:
i'm not taking his IRL into account. i know first had what it can do to your team... Kaiser & JJ didn't complete there training and spent there best seasons with poor GS because IRL didn't allow me to manage it well... (they were NT worthy players but could have been starters...)