Rate my Transfer: Curtis Main to Aberdeen

courtesy of Andrew Milligan (PA Wire)

courtesy of Andrew Milligan (PA Wire)

written by @TheGersReport

Derek McInnes has been looking to add to his forward ranks a while now. Back in December 2018, he outlined his long-standing desire to add more goals from his forward group.

I have been trying to add to the top end of the pitch for a while, I tried to get a creative player in during the summer, we were close to getting one ore two things done. So we do feel we have missed that and maybe that extra goal threat which can sometimes help in tight games.

We tried to bring a striker in in the summer. We put bids in for four or five, maybe more than that, home and abroad. None of the offers were enough money to persuade the clubs to sell their striker. That was disappointing that we couldn’t increase our offer enough.
— Derek McInnes, December 2018 (source: Football Paradise)

McInnes finally got his man last week by completing a deal to sign Curtis Main to a two-year contract. Main has been on Aberdeen’s radar since the spring.

This is a bizarre move because Main has shown few indicators that he can actually be relied upon to be that “extra goal threat” that McInnes is looking for.

His goals per 90 rate of 0.11 last season represents a Goals Above Average of -0.21. Goals Above Average (GAA) takes a forward's non-penalty goals per 90 & looks at it in relation to the average output of forwards in the league over the past five seasons. (For more on this stat, here’s a succinct reference I put together last summer).

It really seems like Main’s perception as a goal scorer is rooted in the hot start he had for Motherwell back in his first few weeks with the club.


In his first five matches he scored four goals.

He was a sensation.

He made everyone forget the loss of Louis Moult.

In those first five matches, Main averaged 0.85 goals per 90 minutes. Since then, he has scored four non-penalty goals in over 3,000 minutes for a per 90 average of 0.11.

courtesy of PA

courtesy of PA

So…who is the real Curtis Main? Is there a middle ground between those two polarized goal rates?

The graph below represents Main’s annual Goals Above Average & Goals Above Replacement rates that are adjusted for each level he has played at - from England’s League Two, to League One, to the English Championship. (For more on Goals Above Replacement, see this post on Eamonn Brophy).

Only seasons in which he played 400 minutes of league football are included.

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The way to read this visual is to use that 0.00 line as the baseline. The black line measures his Goals Above Average…whenever it’s above the 0.00 line, it reflects an above average goal rate of that level of football & when it’s below it represents a below average goal rate.

The red line represents his Goals Above Replacement for that level. Whenever that line is close to 0.00 (or below) it means that he is scoring at a rate that would easily be replaced by the next forward in the team’s squad. This is an indicator that the striker needs to be considered for being removed from the lineup because he is scoring at a rate that is worse then 80% of the forwards at that level.

What really sticks out is that Main has only been an above average forward for the level he was playing once, back in 2012-13, when he scored three goals in 656 minutes as a 20-year old for Middlesbrough. He followed that up the next season with a Goals Above Average rate of -0.18. Even as he dropped down to League One, he never had a season in which he had a positive GAA rate.

The closest he came was when he averaged 0.288 goals per 90 in 2014-15 with Doncaster. The average goal rate for League One forwards is 0.288.

Since that 2012-13 season, Main’s peak has been an average League One striker. Ever since then his goal rate has plummeted to the point he had a Goals Above Replacement rate of -0.09 last season.

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Motherwell now will get the chance to replace Curtis Main.

Aberdeen? Well, they have brought in a forward with one of the worst goal rates in the past six seasons. His scoring rate last season was on par with Graham Cummins in 2017-18 for St. Johnstone & Ryan Dow in 2014-15 for Dundee United. Cummins now plays in Ireland & Dow played in Scotland’s League Two last season.

Meanwhile, Main has leveraged his output with Motherwell with a move up the league table to Aberdeen.


Let’s take a look at the underlying numbers to see if there is any hope that Main is primed for a bounce back from becoming the next Graham Cummins.

The visual below shows how his underlying goal scoring numbers compares to the rest of the forwards in the Scottish Premiership last season.

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Ooooooofffffff…that’s bad. Like really bad. The only somewhat positve output last season was that only 50% of the forwards who played at least 700 minutes averaged more open play shots per 90.

Main’s Projected Goals per 90 (first introduced here) was 0.23, which is actually double Main’s actual goal rate of 0.11.

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So, does that mean there is hope? Main’s Expected Shooting Percentage suggests he should have scored on 27% of his Shots on Target, while he only scored on 16%.

An optimist would say that there are more goals coming from Main. The realist (me) would suggest that while Main may be due for a slight increase in scoring, the reality is that his Projected Goal rate is the equivalent to a Goals Above Average rate of -0.10. That would basically equal Steve May’s rate from 2017-18.

So, while Derek McInnes was looking to add more goals to his frontline…he ended up getting the second coming of Stevie May (the guy who averaged 0.00 goals per 90 last season).

The Modern Fitba Rating of Aberdeen's signing of Curtis Main?

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Some notes…

  • Stats are courtesy of data provided by Ortec Sports.

  • Last summer I had a mini-series of Rate my Transfer posts. The first one looked at Hearts' signing of Steven MacLean, while second reviewed Aberdeen's signing of Lewis Ferguson, & the final one looked at Hibs’ signing of Florian Kamberi. Looking back I was two for three.

  • Could we have seen the demise of Curtis Main last summer? Let’s look at his underlying numbers from 2017-18…

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  • What can be learned here? Well, Main needs A LOT of shots in order to get anywhere close to being an average striker. Even then, his Expected rates for Shot Accuracy, Shooting Percentage & then Conversion Rate tell you there is a real shot selection issue here. Part of that may come down to Motherwell’s style of play, but given his career of being bad - I’d say a lot of that comes down to Main as well.

  • If we had looked at this visual last summer, the warning would be if the shots begin to dry up (they did), the finishing numbers here are an indicator of a bad goal scorer. Main went from slightly below average, to one of the worst strikers the league has seen in the past five seasons.

  • This was written under the influence of the Night Marchers & French Vanilla.