Sure; certain positions in many sports are advantageous to players of different sizes. That was acknowledged by several replies upthread.
But, does it really matter to someone who’s wagering on a soccer match to know the exact weights of the players?
It doesn’t matter much. If I see Lionel Messi playing against Zlatan Ibrahimovic, I can easily see that the latter probaly weighs 30 kg more than the former and is 30 cm taller, but that won’t tell me who’s the greater player. They’re both great, but physically different with different skills.
Well, yes. If one side is filled to the brim with small, technically gifted playmakers, then a backline of big dudes is going to attempt to dominate them physically, man to man. OTH, if said side has large strapping forwards, then its likely that the defence is going use positioning to deny space.
Yes, but an observer could describe or evaluate the sizes of those teams, in the way you just described, from observation alone, or qualitative descriptions from other observers. Knowing the exact weights wouldn’t be necessary.
In the WC QF between Brazil and Belgium, seeing Fellaini being used to man mark Neymar was a good illustration of how knowing height and weight can be useful. His theatrics aside, Neymar is bigger than he looks, so dominating him physically is harder than doing it with say Messi or Xavi. Putting such a physical mismatch on the other hand means he spend sthe night getting beaten like a red headed stepchild.
It used to be more common to mark a crucial player in the past by robust defenders (Maradona always had to fight them), but I’ve seen physically weaker players play rings around their marks, so that doesn’t always work out.