The biggest criticism of the Spaniard so far is that he doesn't know his best eleven. Unless he was following in the footsteps of his mate Mourinho and being especially stubborn, surely even he'd have to admit this was true. Yet the arrival of 13 new players - albeit some returning after loan spells - was always going to require a settling in period.
While performances so far have been more mixed than results would suggest, you'd like to think the lessons of these early season notes will stand Karanka in good stead as he strives for the right formula (in terms of personnel at least, since it's fairly clear he wants to play 4-2-3-1).
So, what might he have learned so far? Here's my guess at the contents of Karanka's casebook:
Costel Pantilimon seems to be the settled choice in goal. Yet, while his towering presence at the back is welcome he does need to learn to keep his cool a little better. Opposition managers will certainly fancy their chances at putting him off at corners. Luke Steele looks to be a smart choice as experienced back up should the Romanian lose either his temper or his form and deserves to start cup games to keep sharp should his moment arrive.
Sam Byram looks to be an astute capture from West Ham. He was a classy performer for Leeds at this level and should be comfortable on the ball in both defensive and attacking positions once he's settled down. Darikwa has the athleticism required to be a modern full back, but probably lacks the decisiveness needed in both boxes to be first choice. In fact, the decision over Tendayi demonstrates the question the manager has to ask about all of his players - will he get me into the top six?
Left back a tricky position? Surely not? To say we've been here before is putting it mildly. In truth, it's too early to judge Jack Robinson but he'll probably be given the chance to make this position his own. However, we're probably going to be left with a dilemma in that Robinson struggles with the attacking side of the role and Ben Osborn lacks the defensive nous needed. Karanka, like countless managers before him, also wants to find a way to get the energy and drive of Osborn into his team and might well - at home at least - choose to use him as an attacking full back.
Soft goals from crosses continue to find their way into the back of the Forest net at a worrying rate and whilst it's wrong to blame these solely on the central defenders it's fair to say we're not yet as solid in this area as we'd all like. As a defender himself, Karanka should have a decent sense of what is required here. So far he's stuck with Danny Fox and Tobias Figueiredo but it wouldn't be a surprise to see changes here soon. The Portuguese defender has looked a little rusty to me - perhaps showing the ill-effects of a shortened pre-season. He's misplaced the odd pass and has tended to rush into tackles or challenges that he shouldn't be getting dragged into, which has left us exposed at times. Fox, meanwhile, has earned praise for his performances and rightly so. Yet, this is probably the best that he can get and teams are getting wise to his raking cross field balls to the right wing. While I admire his Reds resurrection, I can't help but thinking that a Fox-led central defence probably isn't up to scratch for the top six (this question again and the standard the owners and manager have made clear we'll be judged on this campaign). I certainly wouldn't be surprised to see Michael Dawson and/or Michael Hefele blooded into the team soon to add strength and aerial prowess to the team. Hefele's bubbly personality might well help to settle a few nerves too.
It seems increasingly clear that the manager has an 'either/or' choice when it comes to Jack Colback and Ben Watson. Fielding both makes us a little too defensive and pedestrian and we have a better balance when we have one 'destroyer' and partner them with a more creative player who can drive forwards with the ball and link the midfield to the attack better. So far, Adlene Guedioura has excelled in this role and has instigated most of the best play we've mustered. Perhaps in his absence Ben Osborn would have been a better fit against Birmingham and ensured we didn't relinquish as much space and momentum to the opposition. Colback appears to have the nod over Watson at this time, although his style of play is likely to attract cards and maybe even a knock or two, so it pays to have Watson waiting in the wings.
Number 10 role
If Forest really are to challenge for promotion this season, then they're probably going to need something special from Joao Carvalho. It was only right to give Soudani a start on Saturday after his goalscoring exploits, but fielding him behind the striker left too much space between the deeper midfielders and the attackers (although, this might have been made worse by picking both Watson and Colback). Club record signing Carvalho has shown some neat touches and flashes of talent, he now needs to get used to his team mates as much as the rigours of the league. Frustrating as it might be, Soudani might have to settle for a wide berth or a role as an impact sub to chase a game. Ben Osborn might even be a consideration for this number 10 role too, especially if we're up against a team who will have a lot of the ball.
Joe Lolley's thunderous striking was a timely reminder of his talents, and will probably propel him back into the starting XI. Matty Cash has been one of the most impressive performers so far this season, with his pace, work rate, strength and finishing ability helping to secure some decisive goals and is making himself tough to drop. Gil Dias has shown flashes of ability - more so than Diogo Goncalves you'd say - while Soudani might well be worth a place as an attacking wide man who can give more direct support to the central striker. The biggest issue might well be that most of our wide players look better off the bench when sent on to save a game - although I suspect this part of the team is where Karanka is most likely to rotate anyway, depending on whether we're at home or away and who we're playing against.
We desperately need Lewis Grabban to get up and running this season - and I've said before that I feel that a lot rests on his shoulders from a goalscoring perspective. If his form or fitness stop him getting 20 goals then we'll need to get more from Daryl Murphy - and his two goals this season have shown that he can still be a decent finisher - or bring in another player with the money that seems to be coming in from Blackburn for Ben Brereton.
It's still early days yet, of course, but Karanka knows that time is of the essence and that he's being asked to make three seasons' progress in one. While he's got plenty of food for thought in his notebook so far, there might only be four or five positions in which his first choice is totally clear. The time for chopping and changing too much will very soon be over.
Now is when he'll need to be decisive, ruthless and probably lucky if he wants to repay the faith shown in him during the transfer window.