The fact that your followers are soon left in the dust, stats-wise, would help explain the issues mage players are having. Hard to be an effective mage if your "tank" can't, well, tank.
A follower's stats are determined based on the level the player is at when he or she first enters the zone that the follower is in. Once generated, the follower's stats do not increase at all. For example, Lydia is usually one of the first followers players will have access to, and most players receive her at a lower level. As such, most players' Lydias will have low stats for the entire game.
If you have an attachment to a certain follower and wishes to continue to use him or her after he or she has become obsolete, you can update his or her stats by opening the console, clicking the follower in question, typing "disable" and then typing "enable" without the quotation marks. The follower's inventory will remain unaffected, but his or her stats will all be updated to match the player's current level.
-Ripped from UESP.net
By the by, the console is opened with the "` ~" key. On most keyboards its the one left of the "1 !" key.