Celtic don’t often sign first-team players directly from other Scottish Premiership sides so Luke McCowan’s arrival in the summer transfer window took some by surprise. At 26, McCowan had only ever played for Ayr United and Dundee, not possessing the experience profile you usually get from new Celtic signings. That’s not to say he didn’t earn his big move. There can be snobbery about domestic transfers but McCowan was a stand-out in the top flight last season – scoring ten goals and assisting five more. There’s intrigue about what he can offer Celtic over time and the early signs are good. Not…