When things go wrong for managers, especially when the margins are tight, they usually reach into the same grab bag of explanations and excuses. Either the match officials made a mistake or they were "unlucky" -- the "on another day" argument -- or they were lacking something, meaning they panicked, showed a lack of concentration or the classic "opponent wanted it more."

Watch enough football for enough years and you come to understand that, in fact, a lot of what happens is down to randomness. Better teams with better players and better tactics do have an edge and are more likely to win, but stuff goes against the run of play all the time. Moreover, the mental side of the game angle -- especially when dealing with seasoned professionals -- is generally overplayed.

But then you get games like Inter's draw with PSV Eindhoven on Tuesday night, which ultimately sent them crashing down to the Europa League, and you realize how -- at least in the game -- it really was all in the mind. Behold the anatomy of defeat.

There are mitigating circumstances, so let's get them out of the way: Inter had late chances to win and, had they converted, would be celebrating a place in the Champions League's round of 16. Instead, they go out with the same points total and goal difference as Tottenham, who advanced.

As such, so while it's a disaster -- in a sporting sense -- because they controlled their destiny on the night, it is the case that the third-placed team in Serie A finished level with the third-placed team in the Premier League in what was arguably the toughest Champions League group.

Want more? OK, for complicated reasons to do with Financial Fair Play, Inter had squad restrictions that meant they could only include four central midfielders; Joao Mario and Roberto Gagliardini were ineligible.

In turn, those impediments meant that, since Radja Nainggolan and Matias Vecino were injured, manager Luciano Spalletti had no choice but to include Antonio Candreva, who is actually a winger and last started a game back in October, as one of this midfield three vs. PSV.

Luciano Spalletti's Inter won their first two Champions League games, but picked up just two points from their remaining four. Getty

There is also the elephant in the room, which is that Inter are not that good. Lest we forget, they needed late goals to beat Tottenham and draw with Barcelona at home and, in PSV Eindhoven, could easily have been beaten and had goalkeeper Samir Handanovic sent off. PSV, meanwhile, proved to be a tough out for Tottenham and have won 14 of 15 Eredivisie games this season.

But that is the extent of glass-half-full love Inter are going to get in this column. Everything else, starting with their mental approach, was wrong. Not just a little, but a lot, and it may serve as a "how-not-to" manual for them as well as other clubs.

It began straight after Matchday 5 when folks figured out that, for Inter to be sure of advancing, they needed to better whatever result Tottenham got against already-qualified Barcelona at the Camp Nou. The talk was all about whether the Spanish champions would put out a strong XI or, instead, pack it with kids and benchwarmers.

As it was, they opted for the latter to some degree: Carles Alena, who has a whole 43 minutes of Liga experience under his belt, and Juan Miranda, making his first-team debut, both started, as did Thomas Vermaelen and Munir El Haddadi, who have three Liga starts between them.

None of which prevented Barcelona from drawing 1-1 and hitting the woodwork twice (ironically via one of the long list of Inter cast-offs who went on to achieve greater things elsewhere, Philippe Coutinho).

Such was the focus on the Barca-Tottenham game -- there was even a debate whether fans in the San Siro should be kept updated via the Jumbotron, as if smartphones do not exist -- that everyone associated with Inter seemed to forget about PSV.

As a result, when Ousmane Dembele put Barca ahead after six minutes, there was relief and overconfidence all around... only for that to turn to despair when Hirving "Chucky" Lozano's goal sent Inter crashing into their own personalized horror flick seven minutes later.

Borja Valero said afterward they were "too frenzied and frenetic" which, if anything is a bit of an understatement. They piled forward like crazed shoppers on the opening day of the Black Friday sales, which meant every PSV counterattack -- Inter also seemed unprepared for the fact that Mark Van Bommel's team, who had nothing else to play for other than to show they could win at the San Siro, is packed with pace -- into an ordeal.

Then, when Mauro Icardi finally netted the equaliser 17 minutes from time, Inter did a 180: All of a sudden, frenzy turned to lame possession. Spurs were still losing in Barcelona so no sweat, let's just make sure we don't give up another goal. When PSV were most vulnerable, Inter did not press for the winner.

That all lasted 12 minutes, whereupon Lucas Moura equalised at the Camp Nou and, suddenly, Inter needed a goal again. There followed another handbrake turn and another, this time fruitless, assault at the Alamo.

The argument proffered is that this sort of playground stuff was a function of Inter's "immaturity" and lack of Champions League experience, since they have been missing from the competition since 2011. Except it does not really hold water. Marcelo Brozovic (26) and Ivan Perisic (29) played in a World Cup final six months ago, while Valero (33), Candreva (31) and Kwadwo Asamoah (30) are all experienced.

Nope, this was no chance and randomness. What happened is on the players and their approach to the game which, in turn, means it's down to the guy responsible for coaching them. Either Spalletti's game plan was wrong or it was right but he was unable to get the players to buy in.

"Don't worry, I'll take responsibility... I always accept criticism, as long as it's not personal," he said (if you look closely at the video, you will see his nose gets that little bit longer as he says it). "The reality is that we weren't able to maintain the necessary calm. We were rattled by their goal and let the game get out of hand. We let ourselves be ruled by our hearts and our emotions, the same ones that we could feel from the fans in the stands."

Kudos to Spalletti for fronting up, but there is no escaping the truth: Inter blew it upstairs, in their heads and that is a big part of a manager's job. He is the third-highest paid in Serie A. You expect more and, certainly, the nearly 65,000 who show up at every Inter home game, as well as the millions watching around the world, deserve more.