Celtic supporters are far from convinced by the Norwegian's tenure so far.
In football, a manager is judged by results.
So, when one sits top of his league, having also progressed to the league cup semi-finals and Europa League last 32, it's fairly rare for him to receive much criticism.
At Celtic, though, things are a little different. Such is the gulf in class between the Bhoys and their opposition at times, only being four points clear at the top of the SPL is cutting it fine.
Under Neil Lennon, for instance, Celtic were a Champions League side, one that led the domestic standings with pride - and by some distance.
Under Ronny Deila, it seems to have been an uphill battle ever since Celtic were knocked out at the Champions League qualifying rounds.
Yes, the Hoops are still top of the SPL and were on a winning league run until yesterday, while a cup semi-final against Rangers lies in wait, so too Inter Milan in Europe. But, even when Celtic have won, supporters have been unconvinced by their manager.
Everything from Deila's team selections to his curiously quiet manner on the touchline have got fans asking one question: is the Norwegian good enough to manage Celtic?
So far, the results have kept coming for Celtic under Deila - for the most part - but the performances have not. If scorelines like yesterday's become an increasingly regular occurrence, however, the 39-year-old will fast come under heavy scrutiny.
For Celtic fans are already far from convinced.