I don't think Jet2 give a sh1t about recruiting the "right" (as we, the pilots, would define the word "right") people so to speak. This is a minimum risk venture and is influenced by their bottom line. People will front 25K for a TR as a prerequisite and agree to a 70% contract. They will undergo some degree of assessment; fail it and no TR course. Get on the TR course and fail it, no TR and no job. Cost to Jet2 is limited to nothing. There will be a lot of "fat" in the initial 25K investment which in turn bolsters the bottom line - the overall dictator to the recruitment process.
What's the worst that can happen? Not enough bods to take 70% contracts and SSTRs? You will see some advert for a summer contract for 737/757 rated crew on FlightGlobal in order to plug the gap. Jet2 are trying to enterprise and capitalise first and to be frightfully honest; I don't see them having to go down the contractor route anyway. Oxford Cadets will likely fill the holes.
Someone mentioned about CAA regulations in relation to the
experience ratio of crew. There almost certainly is some sort of regulation, however my feeling is that the current crew composition at Jet2 will be classified as "experienced" (no recruitment of low houred bods since 2007 or something?) For the limited numbers being recruited (FOs at BFS/GLA/EDI??) I wouldn't really be surprised if they filled every space with cadets.