Even at 6m it's too much IMO, unless we see him as a longer term replacement for Egan and aren't giving him a new deal.
He's proven to be a good Championship defender, but he's not great on the ball and is more of a head it kick it centre back. Which assuming we stick with a back 4 next year and Egan & Anel are no longer with us it would be a partnership of Trusty & Worrall - both more old fashioned centre backs. It doesn't fill me with a great deal of confidence and would be a downgrade on both Anel & Egan (but I accept we do need to look at Egan replacements given his age and to freshen up the squad).
I'd be looking at Ronnie Edwards at Peterborough. Apparently the asking price is 10m, if we can stretch to that then it's well worth the additional 4m we'd be spending on Worrall on a young player with a very bright future ahead.