"Could have". Those are the operative words in this case. Leigh must have decided that Danny's injury record and/or general form does not make him a good long term bet. Widnes, on the other hand have a more pressing need right now for such a player and are obviously willing to take the gamble.
The same can be said of Tim Hartley, Danny Hill and Martin McLoughlin. All of whom are POTENTIALLY good players but have poor recent injury/form records, which have lead their previous clubs to see them as not good long term bets and so have allowed them to leave.
I hope I'm wrong but I would be very surprised if we see all four of the above featuring in the majority of our games this season.
Interesting whats the lowdown with McLoughlin and his fiorm/injuries?