There's a saying in the NFL that if you have two quarterbacks then you have none. The same applies to goalkeepers. There are exceptions of course, but most successful teams have a top goalkeeper who is a clear and undisputed No. 1.
Liverpool are edging closer to becoming a successful team again and solving the uncertainty that surrounds their goalkeeping position could be the biggest remaining hurdle to overcome. They have a top quality attack led by centre-forward Roberto Firmino, they've just added a quality central defender in Virgil van Dijk and this summer the centre of their midfield will be strengthened with the arrival of the all-action Naby Keita.
A world-class spine is taking shape but the goalkeeper they need to complete it is almost certainly not currently on their books.
Simon Mignolet spoke earlier this week about the "not healthy" situation he finds himself in after Jurgen Klopp benched him in favour of Loris Karius for the 4-3 win over Manchester City. Klopp has been rotating his keepers for much of the season but revealed before the City game that, form permitting, Karius would now get a run of games to establish himself as Liverpool's No. 1.
How long that run lasts is anybody's guess, because Karius has yet to show anything to suggest he can be the long-term solution. Klopp wants to take an extended look at his young compatriot but that will only be possible if his performances justify his selection.
Mignolet has been dropped before but he has always regained his place quickly. Brendan Rogers once benched him for Brad Jones but had to do an immediate about-face when the Australian meekly shipped three goals in a loss to Manchester United at Old Trafford in December 2014.
History repeated itself a year later when Klopp replaced Mignolet with Adam Bogdan. That short-lived experiment ended when Bogdan dropped the ball at the feet of Nathan Ake just three minutes into what would eventually result in a humbling 3-0 defeat for the Reds at Watford in December 2015.
The Belgian responded well to those setbacks but neither Jones nor Bogdan posed a serious threat to his place. With Karius, it's different. Unlike Jones and Bogdan, Karius was not signed to serve as a backup. Klopp clearly wanted him to be his No. 1 but a preseason injury put that on hold initially.
Once Karius regained fitness, he was given the opportunity to make the position his own. It didn't go well. He looked overawed and after a particularly poor performance at Bournemouth (in December 2016), when the Reds blew a 3-1 lead and lost 4-3, Klopp turned once more to Mignolet.
He played well in the second half of last season and helped Liverpool secure a top-four finish. He deservedly began this season as first choice but his grip on the position always felt somewhat tenuous, with Karius being given the nod for Champions League fixtures as well as starting the occasional Premier League game, too.
The sense was that Klopp wanted Karius to be his first choice but in the interest of fairness and consistency he needed Mignolet to "play his way out of the team." A costly error in a 3-3 draw at Arsenal in -- you've guessed it -- December, seems to have been the watershed moment for the Belgian. Klopp did not drop him immediately as that's not his style, but that mistake probably made Klopp's mind up once and for all.
Mignolet has hinted that he may need to move on because he cannot be sitting on the bench at this stage of his career, especially with a World Cup place at stake. If it were just a case of seeing off the challenge of Karius, things might be different as that's a battle he probably feels he can win. Mignolet's problem is not Karius -- it's the likelihood that Klopp will go out this summer and spend big on a top goalkeeper.
Roma's Alisson Becker and Atletico Madrid's Jan Oblak are rumoured to be potential summer targets. If either of those were to come in, Mignolet could not compete and at this point in his career probably would not want to.
If a club he fancied came in for him this month, it would make sense for Mignolet to leave. It would probably suit Liverpool too, but only if the offer was too good to turn down. Moving Mignolet on in this transfer window might also benefit Karius, who -- like Mignolet -- has been playing this season with the fear that any mistake could cost him his spot.
The risk in selling Mignolet is that Karius might not be up to the job. In that scenario, Klopp would be forced to turn to Danny Ward. In the eyes of many supporters that would be no bad thing, but it would undoubtedly be a gamble due to the Welshman's lack of top-level experience.
If nothing happens and Mignolet is still at Anfield when this transfer window closes, don't bet against him regaining his place before the end of the season. Beyond that though, his future almost certainly lies elsewhere as Liverpool are ready to compete at a level where good is no longer enough. They need great.