Are some players programmed to perform badly no matter what?

I ask because I bought a striker at the start of the season. He's a 4 star player at my level, 20 years old. I always have him at 80% or higher condition, very good or superb moral and my team is second on the league as I win most of my games and yet he always performs badly. In 14 matches he's scored just 2 goals and has 1 assist and gets ratings of 5 or 6.

Any explanations?