I don't think this holds up at all, barring the Premier League seasons and double figures up there for a striker in a promoted side is often the exception rather than the rule.
In the Championship, there's only really the Cardiff promotion season and this season that you could say a striker has struggled to reach double figures and I think it's guaranteed Watmore would have if he'd played the full 46 games, he got 9 in 30.
Even last season, Assombalonga got 5 in 8 games under him.
Cardiff in 16/17, he took over with them in the relegation zone in October and Zohore scored 12 goals in 25 games for him.
Rotherham in 2016, he was there for 16 games and took over a side 7 points from safety, Derbyshire and Best both got 4 goals in those 16 games.
That's in a third of a season so I think there's a fair chance one would have got to double figures if he'd had the full season.
Becchio got 5 in 15 games under Warnock in 2012 and then 16 in 26 games under Warnock at Leeds in 2012/13, before being sold in January.
Taraabt got 19 and Helguson got 13 at QPR in 2010/11
Ambrose got 15 at Crystal Palace in 2009/10
Morrison got 16 in 2007/08, though 2 were before Warnock took over.