No, they just aren't very good, its really that simple.
The way some people on here go on about experience, if experience was ALL it was about, every single 34 yr old defender would be equally good as each other, there would never be a 20 yr old player who was better than a 25yr old player, etc, etc.
Experience makes marginal amounts of difference, a crap player is a crap player no matter how many games he's played. Likewise a world class talent will show how good he is straight away.
If thats not true, and its all experience, name me more than 3 players who were world class at 30, and crap at 20, infact name me 5 players in the premier league who improved massively between 20 and 30. I can name more who got worse and put in less effort as they got cushy pay checks, than those who got better.