It wasn't so long ago that, in a time of need, Mauricio Pochettino would turn to Vincent Janssen.

In the pair of meetings with AS Monaco in the 2016-17 Champions League group stage, Janssen was introduced from the bench to try and overturn a 2-1 deficit. Both times, Tottenham Hotspur bumped at the principality club's defense like a frustrated housefly trying to breach a closed bathroom window. Both times, the scoreline stayed the same.

Janssen scored just two goals from open play that season, but, through a lack of alternatives, Pochettino was forced to persevere with the diffident Dutchman.

In spite of spiraling construction costs for replacing White Hart Lane, Pochettino has since somehow managed to assemble a bulkier and more varied roster. Wednesday's damaging 2-2 Champions League draw at PSV Eindhoven, however, suggests the tweaking is not over for the Argentinian. There are clear improvements in his squad, but there appears to be an inescapable state of transition in north London.

Rather than Janssen being afraid of playing anything other than the safe option, Tottenham now possess Lucas Moura, who in the ninth minute produced a sublime pirouette on the white paint of the left flank before scoring Spurs' first goal a half an hour later. He was an under-the-radar buy in January - only Toni Kroos and Dani Alves created more chances in the 2016-17 Champions League season - and he began this term with three goals in his opening three Premier League games.

Kieran Trippier, whose gradual inheritance of a regular starting berth ensured Kyle Walker's £50-million sale wasn't particularly missed, eclipsed everyone else on the park with eight key passes, one of which set up Lucas' goal. Erik Lamela, arguably the first player to properly comprehend Pochettino's philosophy when he was appointed, showed he is fit and on form in a cameo off the bench after elongated spells in the treatment room.

The way Pochettino has been able to accommodate the sales prescribed by chairman Daniel Levy and injuries to a previously thin squad add further bullet points to the talented boss' lengthy curriculum vitae, but the increasing want for something tangible in north London - namely silverware - means errors like the ones committed by Hugo Lloris and Toby Alderweireld in Eindhoven merit greater scrutiny.

Lloris mindlessly upended Hirving Lozano for a deserved red card and, eight minutes later, watched PSV's late leveler from the dressing room. This isn't a one-off. He rushed out of his goal at Wembley earlier this month, giving Philippe Coutinho an easy opportunity to put Barcelona ahead. Lloris was also culpable for a blunder at Chelsea at the start of April, and had an awful error in the World Cup final against Croatia largely forgotten because France were already en route to glory.

At 31, what appears to be a downturn in quality from Lloris is ahead of schedule. There may be external factors to his struggles (he was discovered by police covered in his own vomit when operating a vehicle in central London last month) but his form, or lack thereof, cannot be tolerated by a team with Tottenham's aspirations. The wider concern for Spurs is that Michel Vorm and Paulo Gazzaniga don't present reasonable replacements for a team vying in the upper echelons of English football.

Then there's Alderweireld. His dawdling after 30 minutes set in motion a result that may eventually condemn Spurs to a best-case scenario of Europa League football after Christmas. Lozano had been giving Ben Davies a tough assignment earlier in the match, so for Alderweireld to switch off with the scuttling attacker on his shoulder was going to be costly, despite the Belgian's best efforts to make amends.

Hanging onto Alderweireld is going to cost Tottenham a lot of money, and it's surprising his exit wasn't brokered amid an already difficult relationship with Pochettino due to dwindling minutes. An unhappy defender who was apparently subject to a £50-million offer from Manchester United in the last transfer window can now leave for nothing next summer when his contract winds down.

Changes are afoot, and Pochettino will have less money to conduct them.

Manchester City romped to the title last season but still signed Riyad Mahrez and unsuccessfully scoured the summer market for a deep-lying midfielder. But, unlike Tottenham's constant tides of change, that was renewal and a means to remain hungry for success. Spurs, meanwhile, are locked in a transition, and just as the squad had been fleshed out to the point that Janssen was made redundant, the older, usually reliable parts seem to be breaking off.

When will the old "they're improving" excuses abate? Will Pochettino stick around long enough to see the spine of Davinson Sanchez, Harry Winks, Dele Alli, Christian Eriksen, and Harry Kane truly reach fruition?

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