Maybe those playstyles just show where certain player can play better. But after all if you have mezzala with poor attacking skills, so he probably not shine here. Or let's say you have targetman but he lack good strenght, height, heading he should be useless. And i see sometimes that for some of players playstyles do dont match with their skills. So it's pretty lame.
So my thoughts that you should look for specific players attributes and which match your desired style of play and upgrade required stats which match it. Those playstyles are just pop up icons whose purpose was primary to milkshake managers money and resources