I'd take the mechanic everyday.
A retired pilot or a rookie may think he's good, might have been good even, but the reality is he might not be as good as he thinks he is nowadays as things change by the hour let alone by the day , its easy to get out of touch.
The mechanic will be working to structures , have a pilots licence and know about the overall picture and the ins and out of the Aircraft not just how to fly / taxi it so if he thinks he has no idea he has a reference or a group of people to bounce ideas off.

Nobody said he had a pilots licence , he's a mechanic

And who mentioned a ' retired ' pilot

I'd not want the pilot fixing the plane , but I'd damn sure not want to mechanic flying it

From coaching 17 men to flying a plane,what a smashing thread drift.

Jenky started it

I remember Murph saying that once he got summoned to do a coaching badge....about the late 80's.

Of course he did it and said the only thing it taught him after sitting though a couple of sessions (being taught by someone who'd never actually coached a real team) was that it made him realise why there were no decent coaches any more.

He always said you can't teach someone how to coach, you can only teach them the rules, and no matter how many badges or levels you have if you haven't got 'it' then you're just wasting your time. His hero was (and still is) Jim Sullivan and said he learned more about coaching from him than he could have learned in a thousand years in a classroom.