I think its a mix of both.
I think as a communicator, he's terrible, but as a club, when going for managers, we have a propensity for hiring egotistical managers who like to punish players. Well, to do that effectively, you have to be able to communicate effectively. I also think he struggled to get information across tactically. However, I do think he was inept for this level of football. I think he was a lot more one dimensional than people would like to admit, depending on high amounts of overloads at Ajax. That worked in Holland as the league is much slower and Ajax were technically and physically superior to any other team they encountered. There's a reason that outside of City, top teams don't have as much fluidity throughout the team, because it opens teams up to counters. At Ajax, the weakness of other teams meant that this couldn't be exploited; in England, that wasn't the case.
The problem with a lot of Dutch managers is that they have playing philosophies that they stick squarely to, and due to believing its superiority to other playing styles, don't really learn or adapt to new styles that may be more effective. It's like they're all given this playbook, and follow the same instructions, but where Cruyff could adapt the rules of this, given the situation, alot of them arrogantly stick to these principles and don't learn how to adapt. Slot and Hiddink being the exceptions. We were so bad last season because ETH did not know how to adapt. He couldn't adapt to our injury crisis, he couldn't adapt our tactics to meet the demands of the league and once his plan A couldn't work, he resorted to trying to completely bypass the midfield. He was extremely one note and his in game management shows his flaws in plain sight. He can't recognize issues, he can't adapt to change and quite frankly, I'm not sure he could read the game. What I saw is a manager who could put shapes together, but didn't know why they worked or didn't worked. He just knew in the past, he'd tried it and it had. As a result, when he needed to adapt it, he couldn't. For example, Pep has had multiple formations since he started at Barca. When he arrived at City, despite having a strong squad, his high possession system struggled immensely to deal with counter attacks. Pep understood why this was the case, aging full backs combined with the amount of players committed high up the pitch having to combat the physicality of teams geared with the strength, pace and power to counter. As a response to this, in 17-18, he started inverting his full backs, using Zinchenko and Delph at LB. In 23-24, ETH bought Mason Mount and planned to go into the season with him playing in central midfield. He'd seen City and Arsenal employ Attacking Midfielders as CM's and assumed based on nothing other than hope, that it would work. He copied their system, mixing it with his own. He exposed Casemiro to so much pressure with his 4141, ending his international career and damaging his reputation, as United were slaughtered week to week, with no change in sight. He didn't know how to press, didn't know how to keep the team compact, didn't know how to create build up opportunities, and more than any other flaw, didn't know how to create opportunities for our striker.