Yup.
This has been discussed on most of the train threads. There isn't enough rolling stock on the line to cope with both the evening service, which is more regular than weekend even at 10pm and the football if all trains were to be 8 cars long.
Apologies for the tag @jackalbion but I'm pretty...
On the Brighton side they were running more or less to time. Two issues; everyone left early and one of the peak trains was only 4 carriages. On the Lewes side as EP says we could see trains leaving half empty.
There are reasons why short formed trains are more likely for evening games but...