I've had some semi-solid players with low WE but good cores. I do try to avoid the 1 WE guys, just because they lose more than they can hope to gain over the off-season. 5 and up seems to be about where I want my cut-off. They make some gains and sometimes raise the WE as much as 1 per season. It's not much, but it does seem to control the regression somewhat. Most important of all though, is that his cores must be playable AS IS, because gains are going to be small even when you can slow down or stop the back-sliding.