Have Sarri's Chelsea reached their mental limit?
Chelsea boss Maurizio Sarri said after Sunday's 2-0 defeat by Everton that his team had reached a "limit" - and that could be true in more ways than one.
The Italian was referring to the difference between his side's first-half performance, which he described as "probably the best 45 minutes of the season", and their second-half display, in which he suggested that a regularly occurring "mental block" occurred.
But perhaps the limit could also apply to his managerial capabilities - after all this is not the first time the 60-year-old has referred to his team's temperament this season.
And it may yet be the actual limit of Chelsea's Premier League top-four ambitions - which would mean they needed to win the Europa League to qualify for next season's Champions League.
Chelsea have reached mental limit, says Sarri
Faced with a crucial game in hand against Marco Silva's side, who had not beaten a top-six team since January 2017, the visitors capitulated in the second half at Goodison Park.
It was a fourth away defeat in five games since the turn of the year - only Fulham have a worse record - and another example of Chelsea being unable to respond if they go behind.
The loss leaves Sarri's side in sixth place in the Premier League, three points behind fourth-placed Arsenal, and facing difficult questions as to whether Sarri is the right man to snap them out of their funk.
What's the problem?
After a first half where Eden Hazard hit the post and Ross Barkley bossed midfield despite constant boos from his former team's supporters, Chelsea produced a second-half display that was inexplicable to Sarri, although Everton should be credited with a huge upturn in their performance.
The worrying aspect for Chelsea fans is that, after seeing their side lose one of nine games over the course of 90 minutes since their 6-0 drubbing by Manchester City in February, their poor away form has come back to haunt them and Sarri seems incapable of turning it around.
"It is difficult for the players to explain the change to me," the former Napoli manager said of the contrast in halves. "It is very difficult for me to explain the change to you. Probably it is a mental block, I think.
"At the moment, this is our limit. If we are able to play like in the first half with consistency then we are in another position in the table. We have this problem because we lost a similar match at Wolverhampton [in December]. We lost again in this way, for us it is a big limit."
Is Sarri the right man to turn it around? Sarri has previously been critical of his players' mentality this season, singling out Hazard at one point despite the Belgian having had a hand in 48% of Chelsea's Premier League goals.
But the former investment banker rode out the headlines which said he was on the brink of getting sacked. And it seems he is likely to continue for the rest of the season, helped by a run to the Europa League quarter-finals, which, if they win the competition, would provide a backdoor route to the Champions League next season.
In usual circumstances, Sarri would hope to get to the summer and then seek to add stronger characters to his squad to try to halt their mental slide in tougher matches.
However, there is a huge stumbling block to that solution: Chelsea's two-year transfer ban, which the club are appealing against.
Fortunately, he will have the services of £58m winger Christian Pulisic and 40 other players on loan to choose from. That is tempered by Hazard's potential departure to Real Madrid and the continuation of Bayern Munich's pursuit of teenage winger Callum Hudson-Odoi, who handed in a transfer request in January over a lack of playing time.
It all leads to the question of whether it may be simpler to try another manager, who might be able to galvanise a team in ways that Sarri cannot.
Chelsea have been through 10 permanent managers since Roman Abramovich took over the club.
Top four not impossible - Sarri
For now, those dilemmas remain in the future and Sarri has not given up hope.
Asked if he was worried about his side's top-four hopes, he said: "If you are speaking about the second half you are right. If we play like the second half in the last eight matches then we are in trouble to arrive in the top four.
"We need to recover only three points [to reach the top four] so I think it's not impossible. I am worried about our mentality but if we play 90 minutes for eight matches like the first half then we can do everything."
Sarri might be buoyed by Chelsea's first-half display, which was impressive, but the crucial aspect was they did not score.
He preferred to start his January signing Gonzalo Higuain, who returned from illness, instead of Olivier Giroud, who scored a midweek Europa League hat-trick against Dynamo Kiev.
As former Tottenham and England winger Chris Waddle said on BBC Radio 5 Live: "Chelsea have only got themselves to blame. They play some wonderful football but they try to score the perfect goal at times instead of putting the ball in the net."
Whether it is team selections, tactics, mentality or results, there are still plenty of conundrums and time is running out for Sarri to prove he can solve them before the end of the season.
Race for the Premier League title
Man City fixtures
Race for the Premier League top four
Crystal Palace (A)
Manchester United (A)
TBC: Cardiff (H)
31 March: Cardiff (A)
30 March: Watford (H)
31 March: Liverpool (A)
1 April: Newcastle (H)
2 April: Wolves (A)
3 April: Crystal Palace
7 April: Everton (A)
8 April: West Ham (H)
7 April: Brighton (H)
15 April: Watford (A)
14 April: Liverpool (A)
13 April: West Ham (H)
13 April: Huddersfield (H)
20 April: Crystal Palace (H)
22 April: Burnley (H)
21 April: Everton (A)
20 April: Manchester City (A)
24 April: Man City (H)
29 April: Leicester (A)
28 April: Man Utd (A)
28 April: Chelsea (H)
27 April: West Ham (H)
4 May: Brighton (H)
4 May: Watford (H)
4 May: Huddersfield (A)
4 May: Bournemouth (A)
12 May: Burnley (A)
12 May: Leicester (A)
12 May: Cardiff (H)
12 May: Everton (H)
TBC: Wolves (A)
TBC: Brighton (H)