When I came up to the majors, I was back up, to the back up, for the position I played. When I finally got my chance to start, I always kept in mind that I was one mistake away from going down to the minors.
Now I'm not saying that all is you need is a bunch of bush league, no talent prospects on your team and they'll win consistently, but teams whose players exhibit the type of approach to playing baseball that Zimmer talked about, get the most out of them and usually exceed expectations.
The Cubs may not be the only team with a bunch of primadonas, as a sense of entitlement runs rampant with many players in baseball today, but many on the Cubs present roster certainly don't understand what a privilege it is to be playing baseball for a living.
Hopefully the new Cub's GM will keep an eye out for this characteristic, as well as talent when deciding what players to acquire.