Neymar's actual stamina is very limited, and his defensive work also. He also loves to complicate things, and is very injury-prone,and not the best mentality. He wouldn't be the right partner for Messi.
But with Haaland we can get:
- A high-level runner: someone who doesn't stop running, at attack and at defence, excellent speed and stamina. This is the type of profile we need to balance the profile of Messi and complete him.
- An excellent finisher, can score from half-chances.
- A good header, very present in the box.
- The ball-control and technique is good for a CF.
- He can also be a target-man and free some spaces for players who will come from behind. This can help Messi get more deadly chances in his favorite zone: the zone14, as a dangerous Haaland will already drag with him 2 defenders marking him.
So we can see that the combination of Messi-Haaland is beneficial for both. It helps get the best of each one of them. Messi with his intelligence, technique, vision and passing-range will serve Haaland very well.