Schalke had 7,090 minutes, so to break into the top 20 Albion would need to contribute around 79 full ninety minutes.
If Barry's not included, it's a tough ask, especially with suspensions and Solly being used sometimes as a substitute.
As far as Premier League minutes played last season are concerned, Manchester United's academy provided the most:
Pogba, Rashford, Lingard (Man United)
Heaton (Burnley)
Keane (Everton)
King (Bournemouth)
Drinkwater (Chelsea)
Simpson (Leicester)
Shawcross (Stoke)
Evans, Fletcher (West Brom)...