Tottenham struggling with injuries and Pochettino's tactical tweaks

There was a time when Mauricio Pochettino was criticised for not having a Plan B; for being too tactically inflexible. Now it has become unclear what Plan A is -- if anything there has been too much tinkering.
Spurs started the season using his favoured 4-2-3-1 formation but after a spell with a 4-1-4-1 system and an unsuccessful trial of a 4-4-2 midfield diamond, he moved to 3-4-2-1.
The catalyst was the limp 1-0 defeat at Manchester United in December, when Kyle Walker and Danny Rose were neutralised. Pochettino opted to deploy the duo as wing-backs in the following game against Hull and the result was a 3-0 win.
It was not a permanent transition but, at the start of January, Tottenham triumphed 4-1 at Watford and then beat Chelsea 2-0 in successive games using that system.
They seemed to have found their optimum formation and the following league result -- an emphatic 4-0 win over bogey team West Bromwich Albion -- only served as further evidence as the north Londoners won their seventh match in a row.
Since then, however, Pochettino has abandoned the 3-4-2-1 system and Spurs have struggled, only winning two of their last six games -- narrowly, against Wycombe Wanderers (4-3) and Middlesbrough (1-0) -- and losing the last two against Liverpool (2-0) and Gent (1-0).
While Pochettino picked a strong lineup in Belgium on Thursday, his tactics were odd and Dele Alli spent the first half on the left flank while Moussa Sissoko played as a left wing-back for much of the second period.
They say you shouldn't change a winning formula, so what has happened and how has it come to this?

The stimulus for the move away from 3-4-2-1 seems to have been the loss of Jan Vertonghen, which was then compounded by Rose's injury, removing two key players on the same side of the pitch.
In short, the deputies -- Kevin Wimmer and Ben Davies -- have proven unable to do the same jobs and Pochettino has been forced to change approach.
The warning signs were there before Vertonghen's absence. Four days after beating Chelsea, Spurs faced Aston Villa in the FA Cup. Wimmer, Davies and a group of other second-string players lined up in the 3-4-2-1 system but, midway through the second half at 0-0, Pochettino had to alter his tactics. Spurs were comfortable at the back but toothless going forward so he rightly swapped one of his three centre-backs for a third attacking midfielder.
Georges-Kevin Nkoudou took up a position on the left flank and immediately set up the opening goal, providing the threat Davies had been unable to offer as a wing-back, due to his lack of pace and dynamism. Meanwhile, Wimmer was pushed into action at Manchester City, deputising for Vertonghen on the left side of a back three in the 3-4-2-1 set-up -- and it went badly.
Spurs were unable to play out from the back due to the intense pressure from Pep Guardiola's side. And although Wimmer was not alone in losing the ball deep inside his own half or playing poorly, he paid the price.
Pochettino switched to four at the back during the first half, and Wimmer was withdrawn at the interval. His replacement, Son Heung-Min, scored the equalising goal as Spurs got away with a 2-2 draw.
Pochettino's "winning formula" did not look so great against Villa and Manchester City, then, and he was right to abandon it on both occasions. Subsequently, Wimmer was also substituted against Wycombe and has not played since.
The result of all of this? In the last four matches Spurs have started with four at the back, with an attacking player in front of Davies and two right-footed centre-backs in Toby Alderweireld and Eric Dier.
On an individual level, Vertonghen and Rose have proven irreplaceable, and the impact on the team's formation has been just as damaging -- Spurs have lacked creativity again, scoring only one goal (a penalty) in four matches.
Pochettino gave it another go on Thursday in Belgium, switching to three at the back in the second half. But he was seemingly so desperate to avoid the Wimmer-Davies combination that he opted to use Davies as the left-sided centre-back and Sissoko as the wing-back. The latter predictably looked like a fish out of water and his replacement Nkoudou did little better.
There is light at the end of the tunnel. Vertonghen could be available to face Fulham in the FA Cup this weekend, and it will be interesting to see whether that immediately prompts a return to 3-4-2-1, or whether Pochettino feels he needs Rose as well.
Either way, a lack of strength in depth has forced Spurs' manager to shelve his most effective system -- a situation which will surely be rectified in the summer.