Struggles and Produces less are 2 different things. Anyone will score more while playing with the Best player in the world . See Nuge and Rattie
Put some more thought into it
...LOL okay you asked
2017-18
McDavid with Draisaitl: 57.4 GF%
McDavid without Draisaitl: 57.8 GF%
Draisaitl without McDavid: 44.2 GF% (that's bad)
2016-17:
McDavid with Draisaitl: 59.4 GF%
Draisaitl without McDavid: 44.2 GF% (again that's bad)
The Oilers gave LD a contract based on the numbers that he put up with McDavid, they should've let him center his own line and given him a contract based on that to see what his true value is. McDavid doesn't need LD to be the player he is (best in the world), LD clearly needs McDavid to be the player Oilers fans think he is.
Comparison sake for the Leafs: Matthews and Marner seldom play together on a line, if they do they really well but Babcock wants them each to drive their own line. That's resulted in both of them being star players without needing the other to be successful.