Jose's Falcao Folly?  (Sky Sports)

Jose Mourinho is the best in the business but has he fallen into a trap in signing Radamel Falcao? Adam Bate looks at the evidence...

Ask John Terry what makes Jose Mourinho so special and the word that usually comes up is detail. So when the Chelsea boss explains what made him sign Radamel Falcao after an unimpressive season at Manchester United, it's natural to assume there has been an in-depth process behind the decision.

"I watched our game against Manchester United a few times," said Mourinho. "I spoke with John and (Gary) Cahill a lot about him and we think the bright movement is there, the movement to get freedom in the box to score goals is there. Our players had difficulty to control him and we feel the potential is there."

Mourinho was referring to the Premier League game between Chelsea and United in April. The only goal of the game was scored by Eden Hazard after Falcao was robbed of possession by Terry - "It all came from that," said Gary Neville on co-commentary for Sky Sports - but Cahill recalls a tough test. "I just remember he was non-stop," said the Chelsea defender.

"He was always pulling you left to right, coming short and running in behind. Even when he wasn't getting a lot of the ball, off the ball I was having to do a lot of running, chasing him and he was moving me around every two minutes. He made that game tough and there was a lot of movement people didn't see because the ball was elsewhere. I had to always be on my toes."

But was this performance that Mourinho studied so closely and quizzed his players about really indicative of Falcao's performances or was it an outlier? Sir Alex Ferguson admitted that he was "always wary of buying players on the back of good tournament performances" after getting caught out on several occasions, but this was just one game.

The statistical evidence suggests that Falcao's efforts against Chelsea were atypical. The Colombian made 60 high-intensity sprints at Stamford Bridge - corroborating Cahill's assessment - which was more than any of his team-mates. But it was also more than in any of his other 25 Premier League appearances last season.

Would Mourinho have felt the same way had he watched the replays of Falcao's performance against Yeovil so intently? And even if the Chelsea game is accepted as the benchmark, how much might Cahill's view of Falcao's threat have been influenced by his previous difficulties against the striker?

After all, Chelsea were on the receiving end of one of Falcao's finest displays - his Super Cup hat-trick against the then Champions League holders, completed inside 45 minutes in Monaco in September 2012. It was a performance that Atletico Madrid coach Diego Simeone referred to as "indescribable" and Cahill certainly had no answer.

The so-called 'availability heuristic' holds that the more available a piece of information is to the memory, the more likely it is to influence your decision, even when the information is irrelevant. It's not a new phenomenon but it could have coloured Cahill's experience, just as it affected Neville when up against iconic Brazilian forward Romario.

Neville has described Romario as "the toughest striker I've ever played against" and his view of the player stemmed back to when United were "torn to shreds" by him in his Barcelona days. Neville also recalled being unnerved by the sight of Romario joking on the halfway line with Ronaldo during a 1997 international in which he scored the only goal of the game.

By the time of the World Club Cup in 2000, Romario was at Vasco da Gama, about to turn 34 and ostensibly past his best. It didn't stop him scoring twice against United and Neville - "both defensive horrors and both down to me" - in what Paul Scholes called 'Fiasco da Gama'. So was Cahill, like Neville, playing the memory of the man instead of the ball?

These memories are not always a bad thing, of course. Neville also recalls feverishly texting his brother after witnessing the vast potential of Sporting's Cristiano Ronaldo in a friendly in Lisbon. "United would never have signed a player because of 90 minutes in a pre-season friendly," said Neville. "But they would probably have concluded it a bit quickly after that."

History is littered with such examples and you don't have to look beyond the current crop of Premier League strikers to find them. Emmanuel Adebayor scored eight goals in nine north London derbies for Arsenal before joining Tottenham. And is it a coincidence that Christian Benteke has scored more goals against Liverpool than any other Premier League club?

If that feels like a reactive approach to recruitment, that doesn't mean it doesn't go on. One of the principles of the Moneyball approach to finding value is that "what he did last was not necessarily what he would do next" but anecdotal evidence continues to be a factor in which players clubs opt to sign.

The situation was flagged up by Rob Mackenzie, now head of player identification at Tottenham, on Twitter last season. "Despite advances in technology, data management and enhanced availability of stats," wrote Mackenzie, "many signings seem to occur as a result of same key reasons." He outlined them as follows:

He used to be a good player and that is what I remember about him. 'If' we can get him to that level again, he will be really good for us.
Somebody knows him personally and he is a good lad and he wants to join the club.
He has played well for an acquaintance of the manager who has recommended him.
He shares the same agent as the key decision maker at the club.
He has played well previously against the team who he has just signed for.

Chelsea supporters might wonder just how many of those boxes the acquisition of Falcao could tick. It doesn't mean that he will not flourish in Chelsea blue. But it does call into question the rationale behind the signing. After all, aside from everything else, why buy a player who plays well against you when you are now the one team he cannot play against?