So now we know. Mauricio Pochettino can't be cloned. Or, to be more exact, his impact is not automatically replicated with a similar scenario.
Pepe Mel's brief and undistinguished West Bromwich Albion career can be interpreted as a failed attempt to produce a Pochettino of the midlands, a Spanish-speaking evangelist for the pressing game who could revolutionise a mid-table team's style of play. Instead, Albion got three wins from 17 games, an extended flirtation with relegation and the impression that Mel's brand of football would require a radical revamp of the playing staff. It was easier to axe the head coach. Albion duly did.
All of which serves to make the original Pochettino more attractive to suitors. And Southampton's stylish and swift progress to eighth place threatens to backfire. Their premier talents, led by Luke Shaw and Adam Lallana, are likely to be lured to bigger clubs. Pochettino appears Tottenham's preferred target to replace the sacked Tim Sherwood.
His appeal is obvious. It dates back to the weeks following his surprise appointment, to a two-month period in the spring of 2013 when first Manchester City, then Liverpool and finally Chelsea were not just overcome but overwhelmed at St Mary's. The results themselves were significant -- especially as, in contrast, Tottenham took one point from a possible 24 against the top four this season -- but so, too, was the manner of them.
While Brendan Rodgers was still talking of inflicting "death by football," Pochettino and his players' preferred style of execution involved incessant running. Favourites were unsettled by the high-tempo pressing. Gareth Barry's bizarre, needless own goal showed how flustered City were. It is little wonder clubs with no pervading ethos admire Pochettino's philosophy.
The exponential improvement most of his squad have produced during his 16-month reign helps, too. Shaw, Lallana, Morgan Schneiderlin, Dejan Lovren and Jay Rodriguez have reached new heights. So, without attracting such attention, have lower-profile players such as Steven Davis, Jack Cork and Jose Fonte.
Apart from Lovren, the Argentine inherited all from Nigel Adkins and, whereas many a manager would want an expensive overhaul at any club, Pochettino may arrive with the promise that he could work with the players in situ. Cash-conscious chairmen and chief executives, especially those such as Tottenham's Daniel Levy, can't help but be tempted. Pochettino appeals to those who feel they have unfulfilled potential in their squad and those who believe previous managers have squandered money alike.
Other figures give an added allure: the statistics showing Southampton had more possession, made more passes, scored more goals and conceded fewer than under Adkins. Yet while Pochettino's methods have proved transferable from Spain to England, there is a cruel, succinct retort to suggestions an overachiever will automatically prosper at a higher level: David Moyes.
Admittedly there is no glass ceiling for sides with his style of play. Juergen Klopp won two Bundesliga titles and reached the Champions League final with a similar focus on pressing. Yet Pochettino's time at Southampton leaves questions unanswered; in some cases because the issues have never arisen.
He has operated with a small squad at St Mary's. It has made it easier for them to have an understanding, to practise and then press as one. It is far harder when squad rotation is required, both because of a bigger pool of players and a more crowded fixture list. Tottenham's perennially lengthy and ultimately ever futile Europa League campaigns make the same sort of continuity difficult to implement. It is true, too, that Saints could not sustain their excellence for 90 minutes per game over a 38-game campaign. They lost a league-high 20 points from winning positions this season, six of them against Tottenham alone. Opponents became accustomed to weathering the storm and responding.
Besides the physical element, there are temperamental factors. Bigger clubs tend to involve bigger egos. Southampton have a youthful group who are easier for a manager to mould and an abnormally high contingent of low-maintenance likely lads, many of them grounded by their years in the lower leagues.
The exception was the club-record signing Dani Osvaldo, who was suspended for a training-ground clash with Fonte before being exiled on loan to Juventus. The damning part is that 15 million-pound striker was Pochettino's recruit, a player he knew from Espanyol. His transfer-market record is mixed, too, with Lovren the sole success, even if that may give another club grounds to employ a director of football, but that has scarcely mattered at Southampton.
However, not every manager is fortunate enough to benefit from such a youth system so buying and integrating additions has a greater significance; should they be of the calibre a top-six club pursues, they tend to come with commensurate cost and complications.
There is a further factor at elite level. It is harder to slink away from the spotlight. Pochettino has maintained the pretence he doesn't speak English during his reign at Southampton. Spurs' previous experience with a manager who preferred to communicate in Spanish, Juande Ramos, did not end well.
That is the problem with big clubs: everything is highlighted, a manager's strengths and shortcomings, his ability and approach, his persona, results and record. Pochettino has many of the qualities to prosper. But as with Moyes, Rodgers and Roberto Martinez before him, until he takes a step up, it is impossible to be quite sure if he will.