The £2.10 difference may be a bit much, but since TAA has come back from his injury he has been posting some pretty impressive PB scores. Takes set pieces, crosses loads and has been picking up quite a few assists. Plus Liverpool have made in to European final and keep a lot of clean sheets
Shaw is nowhere near as attacking and I believe hasn't been getting close to the TAA scores. He is also playing in a team who are in rapid decline (season just gone at least) and who don't keep many clean sheets.
Add to this that Shaw didn't make the last England squad and I think you can see why there is a difference.
I don't hold either BTW so this is just my observations.