How so?
Football as a designated penalty taker, the nba doesn't have a designated free throw shooter and still, the conversion rate is pretty much the same.
Logic dictates that the PK conversion rate would go down, if the player who drew the foul was the one taking the penalty.
Plus, you might want to revert to the article i've posted above, where it says PK conversion rate is down to 58% this World Cup
Just admit that your take of not counting PK's unless you drew the foul yourself is stupid. It's not a big deal, man.