I don't necessarily like the thought of "balance" in the midfield. The players don't really function independent of each other. It's not like you need one guy to do *all* the passing and one guy to do *all* the ball-winning.
If we sign Matuidi, he will play LCM, right? So what if the ball goes to the other side of the pitch, will he run there and win it too? No.
It's about finding your playing style and optimizing it. In the past, I would say we were more successful countering because we didn't have the attack that could hold possession and force the opponent to play more timidly. In that scenario, I might prefer Matuidi.
But now, look at this attack. From left to right you can go Alex Sandro, Higuain, Dybala, Alves. They all hold the ball in possession. Now we swapped Pogba for Pjanic. More possession. The equation is almost exponential for me. I'd prefer to add even more possession players in the midfield because they all amplify each other. There were small examples vs. West Ham. Look at Dybala's effectiveness with Alves and Pjanic instead of Licht and Khedira. There were moments when we held the ball on his side of the pitch with like 20 passes. Yes, it would be nice to enjoy some "tiki taka" moments, especially in the CL.
There's a reason certain players have never fit Barca. It's because you need 11 players to play one style, not 10 or 9.
Can you imagine someone like Matuidi at Barca? Well he will recover balls on his side but the drop in possession % would be huge. Not worth it. Can Pjanic replace Pogba's ball winning, and aerial strength? No. But can our *team* have the ball more so that we don't need to win it back? Yes.
Will Higuain and Dybala get more balls and get them quicker? Yes. Isn't that better? Now imagine even more service in the midfield.