Originally Posted by corners
I'm not one that subscribes to the "going dead" theory. Strings continuously lose tension and thus become less and less stiff as they age are are played with. I would be more inclined to think that the slightly increased stiffness you felt was related to the string movement you noticed. If the strings are getting stuck out of line it means they are starting to slide less freely. They could be dirty, scuffed, have lost too much tension to slide and then snapback. Hard to say. But if they aren't sliding and snapping back you'll get less dwell time and more impact shock. I actually think this is what happens when people say polys "go dead." But who knows?
Dead strings don't snap back due to loss of elasticity. Not because they are dirty, scuffed, or tensioned lower. You could put gut in the mud and it would still snap back. You can cut gut out, restring it into another racquet, and it will still snap back. Why? Because it retains elasticity.
When polys lose elasticity, they stop snapping back, and the stiff feel gets compounded by both the strings direct lack of elasticity (in the direction of the ball impact), and the lack of string movement (again caused by no string elasticity sideways).