All linebackers start the same. They need speed and agility. There isn't a single defensive position that doesn't need speed and agility, first and foremost. Outside of maybe the D.T's or run stopping D.E's
What you do next is where you decide whether he will be a LOLB ROLB or MLB.
http://goallineblitz.com/game/player.pl?player_id=1075435This is a linebacker I am making for middle.
My plan was to get speed and agility to 68. You do this with all players.
Rather than hitting up vision After speed and agility (o.l.b.) I am pumping up str. Now he is becoming a MLB.
Middles do not need as much speed and agility, but they still need a healthy dose to be successful. You don't want to be caught covering a Speedy HB somehow with like 80 speed "because you're playing MLB"