Dummy half play is one of the hardest positions to critique in the game because they're so involved in the game and it isn't really obvious whether or not they're having a good game until you slow the game down although it is certainly possible to get a general sense.
I believe the Broncos have been blessed in the dummy half department for some time now and I've liked the look of McCullough, Baptise, Granville, Cullen & Berrell to name a few. Personally, I've never been a fan of coaches preferring utility value over expertise. That's why Ben Hunt's long stint of playing as a bench utility for 4 seasons doesn't sit well with me. Yes, there was a benefit to it and I believe it worked wonders for his game initially but by 2011, Hook needed to capitilise on his natural playmaking instincts and do all he could to develop them, even if that meant sending him to the Devils or the Capras (or were they the Comets back then?).
In the mean time, I believe it would have been smart to have utilised a specialist in that role and capitilised our strengths in the dummy half position. This is hardly a unique opinion or a captain hindsight observation, although hindsight backs it up as I believe they would have put more pressure on McCullough and provided more expertise than Hunt who outside of the odd moment was patchy and seemingly lacked the nous of a dummy half, largely because he wasn't one.
However, let's cut through all the hypotheticals and focus on the present day. The Broncos can't change the past but they can certainly change the future.
I believe time in Rugby League is precious and while blooding new talent can pay dividends down the line, I also believe fans underestimate the importance of putting your best 17 on the park. When I look at the Broncos roster, I believe Jake is definitely apart of that company and while I believe apart of McCullough's superior form this year has been down to him being able to ride out 70-80 minutes instead of getting the obligatory tap on the shoulder 30 minutes in regardless of performance, I think a 10-20 minute performance from Granville (potentially even more if you run with Alec's idea on the odd occasion) would be very beneficial for the Broncos and give them an edge over their opponents more than a David Hala, David Stagg, Todd Lowrie, Jarrod Wallace or Martin Kennedy stint would.
As for the talent debate, I don't think it's a fair comparison for Granville. McCullough has a better combination with a host of players, including Ben Hunt who he played a lot of junior football with. I'm not buying the point that Granville is giving Hunt more time with the footy or that his service is three times better...all I see at this stage is Jake's ability to take quick scoots out of dummy half which are nice and all but nobody knows that they're on and they usually come on an important tackle of the set, forcing a make-shift dummy half to come in anyways to give Hunt the time to get his kick in...
Keeping in mind too, I don't believe the loss of McCullough was the deciding factor in the match. That's a discredit of Granville's game and he really busted a gut for the Broncos.