There is now a mid-season transfer window, which takes place between match weeks four and five of the ESL Premiership season.
By our estimation this is around early to mid February, but we'll post an update once ESL confirms the correct dates (it's likely March 7th to 12th for CSGO and March 9th to 14th for League of Legends).
During this time, the rosters will be 'unlocked' and the team may change two of its starters and as many subs as it likes. To make changes, captains or managers must email firstname.lastname@example.org with the name, nickname and ESL Play profile of the players involved.
Then there's an end-of-season transfer window, where the teams that qualify for the finals can make one 'emergency' change should they be unable to field a full roster.
The team will also be given five minor penalty points for adding an extra sub at such a late stage.
The changes are listed in ESL UK's updated Premiership rulebook for the spring 2017 split.
"During the mid-season transfer window, rosters will be 'unlocked' and a team may change two of its starters and as many subs as it likes."
Irish players have always counted as one of the three of five UK players that teams must have in their starting roster, and now ESL has rebranded the Premiership logo (with part of the Irish flag) to better reflect that.
And every team that participates in the Premiership will now be guaranteed prize money.
We'll have details of some other potential changes ESL is making in the UK soon.
Image source: ESL Flickr/Ravi Lakhini