The 19-year-old joined Leeds United in 2019 after graduating from the Motherwell academy, where he worked with current first-team manager Hammell.
McKinstry made his debut for Leeds last season against Fulham in an EFL Cup fixture, where he scored in a penalty shootout and made his Premier League debut against Tottenham Hotspur in November.
The midfielder has now rejoined his former club Motherwell on a season-long loan during the current transfer window, and Hammell is sure that he understands what McKinstry is capable of.
The Motherwell manager is of the opinion that McKinstry has benefited from being around the Leeds United senior squad and stressed that the player is a great addition to his squad.
“I’ve worked with Stuart before and know exactly what he is capable of”, Hammell told Motherwell official site.
“He has progressed in his time down south and having the experience of being in and around the first-team has been beneficial for him.
“He is an excellent addition to the squad and I look forward to seeing what he produces this season.”
At Motherwell, McKinstry will ply his trade under Hammell and will be eager to get into the regular matchday squad.