xfip simply adjusts the home runs to reflect league average fly ball to home run rate, so ground ball rate is somewhat accounted for, but it does not differentiate ground balls and line drives. You may feel line drives fluctuate randomly, but if you step outside the box and look at Hutch and Sanchez the difference in line drive rates is real. They both struggle with fastball command, but when hutch leaves it over the middle of the plate he gets crushed. When Sanchez leaves it over the middle of the plate, more times than not he induces weak contact because he has such good late movement. His issues come when he can't find the strike zone. In early games Sanchez ball was flat and wasn't getting the movement and that's when he got crushed. His line drive rate after the first few games when down quite a bit.
You may feel the line drive rate is just an element of luck, but I disagree. The batting average on line drives is .685 vs .239 for ground balls and .207 for fly balls. Line drives are the death of pitchers producing 1.26 runs/out. Fly balls produce .13 runs/out and ground balls .05 runs/out. If we look further, 31% of the balls off hutch are hit hard, vs Sanchez who has 21% of the balls off him hit hard.
Sanchez was also on a path prior to getting injured of reducing the number of walks, which was resulting in better fip and xfip numbers. His season was cut off short and he won't log enough innings to have potentially improve on the numbers that were so damaging in his early starts where he couldn't find the strike zone. I think some of you given the choice would get rid of Sanchez and keep Hutch at the end of the season. Personally I would keep both, because Hutch's issues is fastball command and this is reflected in him getting hit hard. His secondary pitches are swing and miss. Sanchez, needs to develop that change up and this will result in him getting more swing and misses. Both can improve to become very good pitchers...time will tell if the do.