Why Matt O'Riley is already Celtic's most effective number 8 and how he can get even better

A paltry £1.5million was all it took to land the 21-year-old on a four-and-a-half-year deal from English League One side MK Dons in what would turn out to be another excellent piece of recruitment work by the club.

Although it would be Reo Hatate who grabbed most of the headlines in those vital post-winter break results, such as the victories at Tynecastle in January and the 3-0 derby win at Parkhead in February, O’Riley caught the eye too, slotting seamlessly into one of the two ‘free’ number 8 roles in Postecoglou’s midfield three.

The former Fulham man would go on to score four goals and provide two assists before the end of the season, playing a key role as Celtic secured the Premiership title and unlocked group stage football in next season’s Champions League.

Now, ahead of his first full season at Parkhead and following the departure of Tom Rogic, O’Riley could be primed for an even bigger role in the Celtic midfield.

Looking back at his numbers from last season in more detail, it is easy to see why fans will be looking forward to watching a full season of O’Riley in a Celtic shirt.  

The above chart shows his impressive percentile ranks compared to other central midfielders in the Scottish Premiership, with a minimum of 700 minutes played in the second half of the season. 

Although it is always expected that players from Celtic and Rangers will rank highly in these kinds of in-league comparisons, there are still some interesting things that highlight O’Riley’s impact when compared to other players at Celtic that played in a similar role last season. There are also areas of his game, that if improved, could take his performance to an even higher level.

The above set of charts shows O’Riley’s ranks alongside Reo Hatate’s ranks for the same part of the season, as well as David Turnbull and Rogic.

For this analysis, Turnbull and Rogic’s numbers are ranked against other central midfielders in the Scottish Premiership but from the first half of the season, again with a minimum of 700 minutes played in that period.

Turnbull and Rogic did make some appearances after the winter break, with Turnbull adding another goal to his tally and Rogic another three. However, due to injuries and the form of O’Riley and Hatate, neither quite reached 700 mins mark so ranking them for the first half of the season can give a similar sample size to compare all four.

This is not a perfect comparison, with the context of Turnbull and Rogic playing alongside quite a few different players and Postecoglou’s system arguably not as embedded as it would be in the second half of the season.

However, they did play roughly the same number of league minutes, all in those number 8 roles (Turnbull 1,689 minutes and Rogic 1,090 minutes in the first half of the season; O’Riley 1,262 minutes and Hatate 1,098 minutes in the second half) so these charts can still give some insight into O’Riley’s impact on Celtic’s midfield.   

As would be expected, all four players rank very highly in the attacking sections. Turnbull had the highest output of the four with five goals from an expected goal (xG) number of 5.15 and four assists from an impressive expected assists (xA) number of 6.71 in the first half of the season.  

O’Riley scored four from an xG of 2.06 and contributed two assists from an xA of 3.43 while Rogic contributed three goals from an xG of 3.95 and five assists from an xA of 3.9 in the first half of the season. Hatate produced four goals from an xG of just 1.48 and two assists from an xA of 1.48.

Touches in the box are similar across all four, as are their ranks for the number of shots per 90. However, O’Riley looks to be the most efficient when it comes to his shooting. His 46.7 per cent shots-on-target rate gives him the highest rank for that metric out of the four.

Hatate’s 34.5 per cent still sees him rank above average while both Turnbull (26.9 per cent) and Rogic (17.6 per cent) had below-average percentile ranks in the first half of the season for their shots on target percentage numbers. O’Riley’s percentage also compares well to Turnbull’s shots-on-target percentage across the entire season (27.0 per cent) as well as Rogic’s (26.9 per cent).

Looking at the possession section, there isn’t too much to be highlighted. With Celtic’s incredible average possession in the league of 67.3 per cent last season, it is natural to see all four players dominate these ranks. Of the four, though, it is O’Riley and Turnbull who have the slightly higher volume of general passes alongside the better pass completion ranks.

Hatate does also rank highly for passes, as expected, but doesn’t have the same completion rate. This could be that he is attempting more difficult passes which look to split defences, but all four players do have high ranks for dangerous passes (a combination of two passing metrics, key passes per 90 and through balls per 90).

It is in the defensive section where O’Riley’s impact can be seen again. He has the highest rank of the four for positioning, a combination of possession-adjusted (PAdj) interceptions per 90 and shots blocked per 90.

Of course, for Celtic midfielders, the PAdj Interceptions will make up most of this combined score as they are unlikely to be throwing themselves in front of the ball to block shots when they dominate the ball so much.

It was clear from watching O’Riley and Hatate that they brought more energy and work rate off the ball to the Celtic midfield and this is reinforced here. O’Riley averaged 7.26 PAdj interceptions per 90 while Hatate had 6.19 per 90. Compared to Turnbull (4.47 per 90) and Rogic (2.64 per 90) this was a big increase which can also be seen in Callum McGregor’s charts in the first and second half of the season below.

Here we can see a drop off in McGregor’s rank for positioning from the first half of the season compared to the second. Although it might be expected that he would be making more interceptions in that deeper midfield role, he was making by far the most with 8.76 per 90 in the first half of the season.

In the second half, the number drops by over two interceptions per 90 to 6.37, perhaps pointing to less of the defensive work falling on him as O’Riley and Hatate were offering more off the ball compared to Turnbull and Rogic.

It is worth noting Turnbull's impressive rank for his defensive duel win (67.4 per cent) in his defensive numbers as well. This indicates that Turnbull can effectively win the ball back in defensive duels, perhaps more ably than he is given credit for.

However, the difference between those defensive duel win rates is not quite as stark as the PAdj interception numbers, O’Riley still managed a 53.76 per cent win rate for his and was also involved in the most defensive duels of all four, 6.17 compared to Turnbull’s 4.58, Hatate was 5.49 with a 46.27 per cent win rate and Rogic 4.46 with a 51.85 per cent win rate.

Based on these numbers, there is certainly an argument to be made that O’Riley is currently the most effective number 8 off the ball at Celtic - and perhaps all-round too.

So where might O’Riley make improvements? Although he did score four goals, this was a slight overperformance from his xG of 2.06 so putting up a more sustainable number, essentially getting into more goalscoring situations, could be one.

Can he also sustain, and even improve, off the ball? The ability to translate his current rates onto the Champions League stage, where Celtic’s off-the-ball work will be crucial, will be the acid test of this, as it will be for all the players.

It will also be interesting to see how the rumoured signing of a number 6 affects the make-up of Celtic’s midfield with the potential that McGregor could move into one of the 8 roles. 

No matter the midfield make-up next season, with a successful half-season as well as a full pre-season under Postecoglou, O’Riley will be primed to play a key role in it.

He will also have the added motivation of looking to work his way into Denmark’s World Cup plans later this year too after making an impression for their Under-21 side in recent months.

With his undoubted talent and a Champions League platform to come, you wouldn't bet against O’Riley taking his game to a whole new level in the months ahead and grabbing himself a seat on that plane to Qatar.