On 'impact players' IMO, generally, players who make this much difference should start. A kid comes on in the 60th minute and he scores a hattrick. Starter or impact player?
LBS is a strong skillful player with good vision and should start ahead of Conchie, who's strong and improving, but lacks awareness, of threats, of offside, struggles to see or execute a defence splitting pass, score, or beat a man. Not a 10.
Piper? Might turn out to be an impact player, useful in bad conditions, rough pitch, wind and rain, dirty opponents, less so in good conditions when a quick passing game is the plan.
But I'd start him too, at least for a few games, as a traditional 9, but behind Eze.
Which funnily enough is where he played for Birkenhead.
Maybe the question of Piper's best position has been answered.