Without the resolute last line of defence, Tim Sherwood's side would have suffered more than it did against West Ham's frequent bombarding of its penalty box.
Lloris could do little about either of the Hammers' first-half goals—an unfortunate Harry Kane own goal and a Stewart Downing free-kick that the Tottenham wall feebly let through.
The second will have been especially galling for Lloris after doing terrific work in between the goals to keep the lead down. He had first come out to beat the rampant Andy Carroll to a cross and, seconds later, tipped an excellent Matthew Taylor volley past the post.
The France international's presence was similarly vital to Spurs' (relative) dignity in the second half.
Commanding at cross and set pieces in the midst of nervy defending from his team-mates, he was on hand on a couple of other occasions to make a further two saves.
A Mohamed Diame overhead kick was dealt with reasonably comfortably. Lloris coming off his line to deny an unmarked Kevin Nolan through on goal was much trickier, and more the impressive for it.
Despite his own impressive display, few others of the 27-year-old's Spurs team-mates will come away with any credit.
After a positive April from the north London club—securing 10 out of 12 possible points—they reverted to the passive and, at times, inept displays which have marked their worst defeats this season. The common thread being they have all come in big matches against top-four rivals, in derbies, or both.
Lloris spoke in detail about the nature of these abject showings last month, remarking:
Hugo Lloris admits it will be difficult for Spurs to be any worse next season following a torrid league campaign. http://t.co/O8CAfH8CLJ— Sky Sports Football (@SkyFootball) April 24, 2014
It was refreshingly frank insight from a footballer into his team's own failings.
Lloris highlighted the 6-0 away loss to Manchester City in November as being particularly damaging to Spurs' confidence levels, ripping away the concentration and focus he believed they had up until then.
While noting he and his team-mates still retained a "feeling that we can play at a very high level," he was under no illusion as to their problems. Per Sky Sports:
...we know this season that the top-four, top-five teams were better than us so we have to keep working and hope to be better next season. It will be difficult to do worse, especially against the top four or five teams.
I mean, we conceded a lot of bad defeats. This season we had sometimes the feeling that we gave up. We can't allow this kind of behaviour. We have to show more character. We did it in different games but we have to keep our mentality at the best level because in this league you have to be 100 per cent every time you play.
Lloris' call for character largely went unheeded at Upton Park as Tottenham all but failed to fulfill the plan—as detailed prior to the game on the club's official website—Sherwood had laid out for them.
The Spurs boss warned "the transition of play into your back four can happen very quickly", but his defence were still left helplessly on the back-foot after a quick ball forward allowed Downing to run at Younes Kaboul, leading to the centre-back's dismissal.
If Spurs "worked on defending crosses, winning second balls in the midfield," as Sherwood indicated, there was little evidence of it. Nor were they able to "break quickly and dominate possession" when they got the ball.
Make no mistake, this was going to be a tough game. West Ham live for beating Spurs, and in another mediocre campaign for the Hammers, their season (and perhaps Sam Allardyce's job) rested on securing a third win over their capital neighbours.
Defenders Kaboul, Michael Dawson and, later, Vlad Chiriches were given a torrid time by the eager Carroll. In the mood he and others like Diame and Mark Noble were in, it was likely to be a long afternoon even had West Ham not gone in front when they did. On Sherwood's part, he made a notable mistake selecting Gylfi Sigurdsson ahead of Sandro, once again leaving Spurs soft in centre midfield.
But a tough game is what Lloris urged his team-mates to be ready for at any time. Spurs' general inability to "keep [their] mentality at the best level" was hard to fathom after the efforts of recent weeks, even more so their comparative timidness compared to that of a bottom-half opponent.
It was seen in the way Paulinho blindly passed into a crowded area, ignoring Sigurdsson's screams for the ball in open space—an error which led to Kaboul's dismissal. Then again in the way the Brazilian and Emmanuel Adebayor moved out of the way—out of the way—of Downing's free-kick when their job in the wall was to block it.
In the run-up to Diame's overhead-kick attempt, Danny Rose highlighted his frustratingly inconsistent attitude when it comes to applying himself. After weakly losing a 50-50, he barely jogged back into position and, once there, did little to block Downing's cross.
Sherwood rightly praised Lloris post-match:
Tim: "Hugo was top class. He keeps his consistency, his level of professionalism and his performance was of the highest level."— Tottenham Hotspur (@SpursOfficial) May 3, 2014
Amid Spurs' poor performers, a few others deserve some praise.
Kyle Naughton did fine work stopping the Hammers crosses put in from his flank at least, winning six tackles and successfully clearing on five occasions, too—as tallied by Squawka. Christian Eriksen tried hard to bring Spurs forward, a couple of sublime passes to substitute Roberto Soldado going unrewarded. The typically eager Kane was unlucky to be chosen to make way after Kaboul's sending off.
All that is of little consolation, though.
One more match remains for Tottenham before they close the book on the Premier League for another year. The story of 2013-14 undoubtedly would have been a lot messier without the presence of the gallant Frenchman, Lloris.