Will Lennon get transfer funds to strengthen the squad? I take a look at managerial trading since the end of the O’Neill era.
I pick this benchmark as it saw the end of the strategy of a stellar first XI and then kids / cheap squad players to a more nuanced model of Moneyball trading, academy promotion and sell ‘em high.
This is an edited post. Initially I used the data I had collected at the time from media and other sources on transfer fees. The Annual Report and Accounts are the document of record concerning the monetary values involved in the buying and selling of “intangible assets” i.e. players. It will therefore reflect the loan fees, for example, which I would not previously have had.
Strachan (2005-09)
At the time it seemed Strachan was charged with replacing the days of record purchases under O’Neill with more prudent and cost-effective signings. He is rightly praised and remembered as bringing success whilst reducing the overall cost of the squad.
However, with the benefit of hindsight, Strachan had significantly more funds provided to him for transfers than any of his predecessors. Indeed, he is the only net spender since O’Neill (ignoring Mowbray!).

Strachan spent nearly £16m net over four seasons. His costliest purchase (and what a legacy) was Brown for £4.4m. Otherwise he was trading in the £1-2m market with only Vennegoor of Hesselink at £3.4m over that.
In terms of sale, the £6.5m Petrov dollars was easily the highest.
In those days Celtic benefitted from automatic qualification to the Champions League Group Stage – try explaining that to your kids!
Mowbray (2009-10)

The Mowbray reign was short, and was costly in terms of net transfer spend. In fact, £5.9m was spent on a net basis.
The £3.8m for Fortune was the signature signing, offset by Strachan kindly taking McDonald to Middlesbrough for £3.5m. The Keane loan would have been costly.
Lennon (2010-14)
Lennon managed in interesting times. Whilst the Scottish football scene apparently underwent Armageddon, the perceived lack of a rival after the liquidation of Rangers may partly explain the tightening of belts under the Lurgan man.

Alternatively, the modern Celtic of the 21st Century could be argued to have truly started with Lennon. Moneyball signings (playing the Bosman market e.g. Ledley, Matthews, Lustig) and buying just young enough to be off the Big League radar (Wanyama, Van Dijk, Hooper) became the norm. As did negative net spend.
A consideration for Lennon as he ponders the job again is that only in 2 of his 4 seasons did he have a net spend on players.
His biggest signing was Juarez (hands up?) for £3m whilst Wanyama (£12m), McGeady (£9.5m), Ki (£6.3m) and Hooper (£5.25m) were Moneyballed out.
Two Champions League campaigns in four seasons was supplemented by net £5m of incoming transfer lucre. By this stage Celtic managers were averaging around £8-9m outgoings per season.
And the trend was set.
Deila (2014-16)
The Moneyball manager was given around the same per season on average to spend as Lennon (around £8-9m).
Deila’s biggest outlay was Simunovic £2.8m.

However, bringing significant transfer income continued as a trend.
He oversaw the outgoing of Forster £10m and Van Dijk (initial £13m) to the English Premier League,
Overall Deila brought in slightly more than he spent but the extent to which he was supported may surprise.
Rodgers (2016-19)
The former EPL manager, used to proper war chests at Liverpool, was supported to an average of £14.4m per season for outgoing transfers – the highest average of the managers analysed.

However, he brought in over £15m per season, reflecting the upward trajectory of transfer fees in general.
The record fee of £9m for Edouard was eye catching. Ntcham (£4.5m) and Sinclair (£3.5m) were his other signature signings.
Records tumbled at both ends of the balance sheet as £19.8m arrived for Dembele, whilst the Van Dijk dividend continued to deliver with a further £7.5m arriving from Liverpool. Armstrong’s fee of £7.2m is massive for Celtic but tiny by current EPL standards.
Summary
This is not an article about which manager had the best transfer record in terms of hits and misses. The point here is to show that whilst Strachan reduced the squad running costs, he did so with transfer fees at a trading loss that has not been seen since.
Since then, after the Mowbray debacle, Celtic managers have run at a largely break-even basis between money spent and coming in from transfers.
Lennon may get funds, and based on the averages, he can expect to spend around £10m in out goings. But Celtic will recoup around the same at the other end.
Unless the environment changes, this won’t change soon.