Come on Jet2_738 Jet2 are not a young airline, just how long have Channex been around?
Whether they keep them in top condition or not does not eliminate 'aged' problems its as simple as that. J2 engineers do a great job, but drive a long any motorway for a year and yes you'll see the odd S class or Range rover stranded on the hard shoulder but overwhelmingly it is older vehicles, my point is simply this that Jet2/Channex historically have made a business decision to buy aged aircraft because they are less expensive to acquire and it suits their very seasonal business plan. I have no problem with that at all, but you have to expect and plan for higher maintenance costs, again J2 do that, what has changed is consumer legislation has ruled that airline can no longer use unexpected technical problems to doge paying compensation and that applies equally to new aircraft.
To my knowledge J2 does not publish delay information or its despatch rate.