What measurable qualities do you speak of? Tireless running with mediocre outcomes? Fletcher and Park were levels above them and weren’t regular starters for the club.
Obviously I don’t think this new midfield is good enough to win the league, but it is a great starting point to compete for top 4.
I just went to look at Fred's stats. 3.6 tackles (49% success-rate) and interceptions per game:
https://www.premierleague.com/players/5906/Fred/stats
Pogba - 2.1 tackles (68% success rate) and interceptions per game
https://www.premierleague.com/players/3920/Paul-Pogba/stats
McT - 2.5 tackles (54% success rate) and interceptions per game:
https://www.premierleague.com/players/14824/Scott-McTominay/stats
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Eriksen apparently averaged 3.2 tackles and interceptions at mighty Brentford at LCM, while offering impressive control and offensive threat. They also drastically improved their results and possession stats after Eriksen joined:
https://the18.com/en/soccer-entertainment/how-christian-eriksen-transformed-brentford
De Jong averaged 2 tackles (70%+ success rate) and interceptions per game as CM and despite Barca’s higher possession stats. I’ll agree that the proof is in the pudding as to whether he can make the PL transition defensively.
Bruno averaged 2.2 tackles (53% success rate) and interceptions per game:
https://www.premierleague.com/players/23396/Bruno-Fernandes/stats
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As for the DMs who played in recent title-winning sides - Michael Carrick averaged 2.3 (but includes stats from his attacking days and declining years), Fabinho 3.2, Fernandinho 3.7, Kante 5.3(!), Casemiro ~5, Busquets 3.4. Meanwhile, muppet favourite Ruben Neves averaged 3.6 (similar to Fred).
So yes, in my opinion there is every reason to believe that a midfield trio of Eriksen, De Jong and Bruno is more balanced than the previous one of Pogba + Bruno + Mc/Fred. If Eriksen and De Jong can average 2.8 as a double pivot they would be on par, if not better, than a Pogba + Mc/Fred pairing defensively, while offering more in terms of control and attacking output.
Individually - if Pogba plays, he’s a massive defensive burden and loses the ball too often in dangerous positions. if McT/Fred plays instead, they are a control and attacking liability.