Despite a string of impressive results with draws at Arsenal and Manchester City and a win over Bournemouth in recent weeks, Middlesbrough's centre-forward Alvaro Negredo has come in for a plethora of fan and media criticism.
Without a goal to his name since the opening day draw with Stoke City, there have been calls for the big-name summer signing to be benched in favour of David Nugent or, more frequently, Jordan Rhodes.
The former Spain international has been chastised for his movement and finishing, his desire and his inability to create options for his fellow attackers.
The quality of opposition does not seem to crop up in many of these debates - Negredo's lack of goals may be a worry but three of the four last fixtures have been against Arsenal, City and the apparently unstoppable Chelsea. The Spaniard has come close to finding the net in each game.
Negredo has not looked short of confidence
Against Chelsea particularly, the 31-year-old looked sharper in front of goal than in recent weeks. An early run was not picked out by Gaston Ramirez and a sublime touch and volley in the second half almost arrowed into Thibaut Courtois' bottom corner.
That moment of quality did not suggest a forward low on confidence. Nor did his 60-yard lob against City which had Claudio Bravo back-pedalling to tip the inch-perfect shot onto the roof of his net.
Nor did his selfless knock-down for Stewart Downing's goal against the Cherries suggest a player desperate for a goal and unable to provide the other forwards with a target man.
Negredo has had a hand in five goals this season including assists and his effort which forced Maarten Stekelenburg into an own goal at Everton - Boro fans may have been dreaming of a 25-goal season in the summer, but that is not a terrible return considering the shape their campaign has taken.
Despite a promising start against Stoke and Sunderland, Boro have had a tentative first quarter of the season and have only really started to kick into gear in the last four games.
If their form continues against weaker opposition - they face Burnley, Hull City and Swansea City in the next month - it is to be expected that Negredo will have more opportunities than against defences marshalled by Messrs. Guardiola, Wenger and Conte.
The issue for Middlesbrough is not the form of Negredo, but that they do not have a strong enough back-up or partner to really make Karanka think about his options.
Championship strikeforce needs an upgrade
In Rhodes, Nugent and Cristhian Stuani, Boro have a fearsome attacking lineup at Championship level, but that is no longer the level at which they are playing.
In five Premier League seasons, Nugent has passed the five-goal mark only once. Rhodes is an unknown force at this level and despite Stuani's three goals this term, his performances have been incredibly frustrating for the last twelve months.
Rhodes' effect on the club's promotion campaign last season means fans are crying out for him to be given time to settle, but that is time Boro simply do not have.
After 'seven long, cold, hard years in the wilderness', to quote local commentator Mark Drury, Middlesbrough cannot afford to gamble their Premier League status on a poacher unproven at this level.
It is simplistic, but it has often been said that there must be a reason why no Premier League manager has ever taken the gamble on Rhodes as a signing considering his second-tier scoring record. Perhaps Karanka has come to the same conclusion over the course of this season - if so, he must move to replace him in January.
In a one-striker formation, Boro do not need four forwards jostling for the starting spot. Rhodes and Nugent will be on the wishlist of plenty of clubs lower down the footballing ladder and if a sizeable bid comes in, the Teessiders should cut their losses and allow one to leave.
Ideally, Nugent should be the one to leave. Rhodes, at 26, is still in his prime years and can learn from the influence of players like Negredo. But there is no time for sentimentality if he is going to spend his time permanently on the bench.
Boro can afford a financial gamble
Recent form suggests that Boro are good enough to stay up, and can therefore afford to take a financial gamble on a forward. That does not necessarily mean they have to splash £35million on a leading light of the game, but £10-15million can still go a long way.
A differing skill-set to that of Negredo is needed to give opposition managers something to think about. Adama Traore is living proof of the necessity for pace, and there is a sense that Boro could use some younger legs up front from time to time.
Good players to not come cheap in the January window, but Karanka and Steve Gibson are both fully aware of the impact a well-planned mid-season signing can make. Uwe Fuchs '95 and Gaston Ramirez '16 are testament to this.
The under-the-radar acquisition of Victor Anichebe at Sunderland seems to be doing the trick for David Moyes, with the Nigerian forming a partnership with the previously isolated Jermain Defoe.
Middlesbrough have their own former international ploughing a lone furrow up top. He has the quality - now he needs either competition or company.