Shane Duffy seemed like a great idea. A big, strong, experienced EPL and Irish internationalist, captain of his country and a leader by nature and action on the park. What’s not to like?
What follows is a salutary lesson in why football is an inefficient industry when to comes to scouting and recruitment and should send alarm bells ringing for Celtic fans as to the efficacy of the Champions’ operations.
Duffy Benchmark
I benchmark central defenders using two heavily aggregated metrics. Defensive Action Success Rate (DASR) is a % of defensive actions where the ball is won. Possession Win % is the % of winning defensive actions resulting in Celtic possession.
Here is where Duffy compares with Centre Backs since 14/15 when my data starts:

Duffy is up there with the best in terms of, when he wins the ball, it stays won! Over 90% Possession Win % means that he is comparable to Ajer and Jullien who are both at the top of the centre backs Celtic have had in recent years despite what some may tell you.
But the problem is he is not winning enough challenges, and loses out of defensive actions at a rate comparable to Hendry and Ambrose who are down in the left-hand Corner of Sadness of recent centre halves.
Centre back needs to be a position of minimal errors. It’s the last line, central and errors usually lead to opposition chances.

Duffy surpasses Ambrose for errors per 90m. Not something I hoped I’d ever write of anyone. The average is 0.6 per 90m Duffy’s rate (covering over 13 games worth of data now) is double that.
Why is this happening?
Duffy’s errors fall into a pattern of too many fouls, and being dragged out of position to try and win headers (especially) that are not there to be won. Let’s call it over-reach. If you were being kind, you’d say he is trying too hard. And as a fierce-competitor-warrior type used to leading teams, the more errors the more he tries hard to redeem often compounding the issues.
Some of that is no doubt personal style, and at 28 will he change his approach?
A further consideration is that he has often been exposed by the tactical approach Celtic employ under Lennon. The full backs and in particular Frimpong on Duffy’s side, both bomb forward and on the break Celtic are often exposed. Additionally, Duffy has tried to compensate for Frimpong’s likely loss of a header by trying to cover the young Dutchman. This has led to catastrophe and chances and goals conceded as it bends the whole defence out of shape, and Duffy doesn’t have great recovery pace.
This causes anxiety and uncertainty across the line. AC Milan’s first goals saw none of the defenders in the right position and Duffy under the ball. Their second is partially caused by Duffy anticipating having to cover Welsh and the whole back line getting exposed. It’s defending 101 to let your team mate do their job and at least not be out of position if they lose it. Confidence then goes and his body shape is all wrong as Milan broke to score the third as it was in Lille when he needlessly gave away a foul that was wrongly given as a penalty – when your luck is out.
A good game at Aberdeen was undone by hesitancy losing the ball to Wright leading to Hedges scoring. He had one of those horrible runs where every mistake seemed to get punished. His over-reach in the last minute contributed to the panicky defending that resulted in the penalty (how many times has McGregor been the last defender this season when goals have been scored? – there are deeper issues here).
We thought it hilarious when Duffy elbowed Jullien out the way to score at Ross County but when he is elbowing his own keeper out the way to get to a corner as against Lille, this leaves huge gaps elsewhere (as well as being unhealthy for Bain).
The unsightly exposures to the Sparta Prague break finally saw him removed from any more torture for the Motherwell game.
What now?
Rather than bashing Duffy, we should critically evaluate who thought his signing was a good idea and why?
Here is a player with no great pace and little ability to progress the ball (he has the lowest Pass Impect of the centre backs – 7.01 pack passes per 90m compared to 9.43 from Jullien). He appears to mainly have been played in a two yet Celtic started the season wanting to play in a three. It then looked like he was preferred to Jullien (see above for the effectiveness of the Ajer/Jullien axis) which made no sense. See the Huddle Breakdown link at the bottom where @jucojames covers this in more detail.
He has largely played for teams defending deep and lacking possession. Now he is being asked to cover space left by vacant full backs and to bring the ball out from the back and break initial pressing lines. He isn’t that player and at 28 likely never was or will be.
The Duffy singing has been disastrous and probably through no fault of the lad who wanted to play for Celtic. The questions this raises about tactics, strategy and recruitment should give cause for concern.
The issues raised in this blog were discussed in more detail on The Huddle Breakdown Episode 2. Please follow and share.