Think this is a very good post and was how I was thinking with regards Arsenal.
There's no doubt his height is a concern, but it's not just about height. I take our own Ben White for example, not the tallest for a defender, and he did seem to get bullied a few times, I'm thinking about against the likes of Toney, Callum Wilson specifically.
But, I don't think he is intelligent enough at times to compensate for this. He also could be more aggressive, anticipate better etc. Defenders can always play someone bigger than them, top defenders are intelligent enough to know how to handle that, compete more for 2nd balls etc.
To be fair to White, his team mates didn't help him in those games as we were passive all over the pitch, but Martinez seems to have that aggressiveness over White. Ironically, I believe our conceding from set pieces was very good last season, so it shows it can be worked on tactically and it's not all about height.
Like you say though, there's another way to play against these teams, and that's more the Man City way, of raising the technical floor of the team, to keep the ball much better and squeeze them further up the pitch away from your goal. That's why I think we are interested, and why Ten Hag will be interested as well. Our worst performances against Brentford, Palace, Newcastle, Everton, Spurs etc, was where teams were aggressive and pushed right on us, but we brought that on by being unable to play our way out and play under pressure.
Our technical level of our team drops massively when our first choice players are out, so watching the likes of Tavares, Holding etc try and play out was scary. I think thats the thing Arteta is trying to raise most this summer, and I think ETH will be doing likewise at Utd.