WE take a look at some of the talking points after Millwall suffered their second successive league defeat at The Den.
The Lions went ahead through Fred Onyedinma before goals from Sam Winnall and Alfie Mawson gave Barnsley the lead.
It looked as though Onyedinma had rescued a point for his side when he headed home with eight minutes left, but Lewin Nyatanga had the last word when he nodded the winner past David Forde.
From Millwall’s problems at home to the question of the side’s flexibility, we analyse the latest result and what it means.
1. Home discomforts
A feature before the last three home games was opposition managers and players almost reflexively trotting out the same platitudes about how difficult it is for away sides to play at The Den.
In truth, all the evidence shows the fear factor is actually working for away teams and against the Millwall players.
It was very noticeable on Tuesday night that the atmosphere, even in this early part of the season, was strained. It was as if the home fans were waiting for someone to make a mistake on the pitch.
And the Lions players felt it too when one would have thought there would have been a fire-and-brimstone start to the game to attempt to get the Coventry result out of the collective system.
There was a nervousness in defence and tentativeness to attacks that only evaporated once Onyedinma scored the opener on 27 minutes.
The weight visibly lifted off the side at that point and they quickly could have gone 3-0 up as they began playing with a new zest.
Shaun Williams was inches away from connecting with a cross that would have doubled the lead before Lee Gregory bundled the ball over the line only for referee Dean Whitestone to rule the striker had impeded keeper Adam Davies.
Who knows what that would have done for confidence but instead Barnsley’s equaliser brought back the same doubts.
Neil Harris wants to play the traditional ‘Millwall’ way but is this signalling to opposition sides that there won’t be any flexibility in approach and therefore they have a head start in how they set up to nullify Millwall’s threats?
Coventry showed the value in being able to switch between formations last Saturday.
On the way out of the press lounge Tony Mowbray was asked whether he had deployed a 4-4-1-1, a 4-3-3 or 4-5-1.
“What does it matter what the numbers are?” he responded. “It’s just moving a player 10 yards further forward or 10 yards back at the end of the day.”
But Coventry had started with James Maddison in the space between Millwall’s midfield and defence in a 4-4-1-1 formation and had switched to 4-3-3 with substitute Jacob Murphy on the left before Jim O’Brien’s fourth goal.
Millwall have arguably been a bit linear, particularly at home where the initiative falls on the hosts to move their opponents around the pitch to create space, just as Coventry did when Maddison picked out Ruben Lameiras for the Sky Blues’ second goal last weekend.
Having the flexibility of, say, being able to switch to a 4-4-1-1 would also have the added benefit of being able move Onyedinma into the centre should League One defences wise up and decide to double up on him out wide.
The 18-year-old said during the summer his favourite position is behind the main striker and it would certainly be interesting to see how good he could get without having to do the energy-sapping defensive work that playing in a wide position requires.
Added to that again, Shane Ferguson was often left exposed against Barnsley on Tuesday night with Ed Upson initially in front of him before Onyedinma switched to the left.
Barnsley set up with two wingers holding their width either side of Winnall and Marley Watkins was able to push way up on the right to exploit the space outside and behind his direct opponent.
It took a while for that threat to be identified but being able to adapt between formations would lend itself to quickly remedying evident problems.
3. Set-piece setbacks
At least there will be an easier starting point from which to begin corrective action before the squad travel to Scunthorpe.
Barnsley’s three goals came, straightforwardly, from balls into the Millwall box that weren’t dealt with. Two were second balls that fell to Tykes players, while the winner came from a cross from deep that wasn’t exactly whipped in at pace.
Apart from the frustration of conceding three goals from set-pieces, looking at the actual circumstances surrounding Barnsley’s second and third goals will have been especially galling.
Harris said afterwards he had given his players responsibility to decide who to pick up when Barnsley won a free-kick or corner.
And there should have been time for Millwall to set defensively as there were a number of seconds between the awarding of both free-kicks and when they were taken.
It was as if the side were so focused on not conceding from play that they switched off when they should have been concentrating on the fundamentals of defending balls into their box.