3-man back line... attributes for a covering defender?

I just started a new save as Wolves in England. They don't have much talent at fullback, and I have some good prospects at CB, so I want to try to play a 3-man back line. Currently I have it set up with two defenders on "defend" and one on "cover". I think this is a good idea because it doesn't leavetoo big of a gap between the defenders and remains symmetrical. However, I'm not sure which defender to play as the covering one. Do I go with the fast, athletic defender since he has the speed to get to any balls the other defenders don't get to? Or do I play a slower defender there under the idea that he doesn't have as much space to cover and doesn't have to match up against an athletic striker?

Personally I always prefer a quicker defender as the covering one. I could be way off the mark with what how the game works but my thinking is the same as yours, if he's quick he will be better at 'covering' any loose balls or gaps.

Go to Tactics -> Player Instructions and you can see what attributes are good to have for each position and role.

Positioning, concentration, pace, acceleration, as well as the standard defender attributes (first touch, tackling, strength etc). I play with a lightning quick covering CB and he's absolute quality, only 20 years old and has made nearly 100 Premier League appearances for me already.

Go to Tactics -> Player Instructions and you can see what attributes are good to have for each position and role.

I believe that it shows the same attributes for all three defensive rolls of cover, defend, and stopper.

I believe that it shows the same attributes for all three defensive rolls of cover, defend, and stopper.

For central defender roles, both stopper and cover has two extra attributes. Stopper has aggression and bravery, since hes going to push up farther and win balls higher up the pitch, while cover has anticipation and acceleration since he'll have to anticipate the danger coming to be able to sweep up loose balls and need the acceleration to get to top speed quickly to get there before the striker. Well, at least that's how I've interpreted it. Haven't used either of those roles myself but considering using a cover and a defend role, with the DM acting as the stopper, so my cover defender can try to stop those pesky through balls.

Answering OP's question though, would definitely go with the faster CB as the cover, unless he has atrocious mental attributes.

For central defender roles, both stopper and cover has two extra attributes. Stopper has aggression and bravery, since hes going to push up farther and win balls higher up the pitch, while cover has anticipation and acceleration since he'll have to anticipate the danger coming to be able to sweep up loose balls and need the acceleration to get to top speed quickly to get there before the striker. Well, at least that's how I've interpreted it. Haven't used either of those roles myself but considering using a cover and a defend role, with the DM acting as the stopper, so my cover defender can try to stop those pesky through balls.

Answering OP's question though, would definitely go with the faster CB as the cover, unless he has atrocious mental attributes.

It's just my opinion but I agree with slich completely, Anticipation/Acc will be your CD-Cover main attributes here because his main job is to intercept those through passes, worst case scenario is this when your defenders can contain the attackers just outside the box and your opponent has to pass the ball around to find space between your defenders, in this case they'll try to go to their wings or have a midfield go up to help open up space and make that through pass. In this scenario your CDs and their strikers are pretty much on top of each other and when those through pass came, the player with the highest anticipation will (usually) the first to run to get the ball, so this is why you need your CD-C to have a high ant/acceleration... and concentration too of course (otherwise you'd find at times your CD just... stand there... even if he has high ant/acc xD)

Anticipation, concentration and acceleration are important for a cover (as well as the obvious ones) To see if a player can play that role well go to the player and in the attributes tab there is a view role in the top right, click on central defender cover and it will highlight what attributes you need. Also if you are playing against two strikers, i try to have him as my most technically gifted player as he will have a lot of the ball (the strikers will mark your other two centrebacks) so he can start your attack.

I believe that it shows the same attributes for all three defensive rolls of cover, defend, and stopper.

Not in my game. You can change the role and duty in a drop down menu.