You could store the previous team in a variable local to your import script. Then check if the field is empty.
If [ IsEmpty ( yourtable::yourfield ) ]
Set Field [ yourtable::yourfield; $team ]
Set Variable [ $team; yourtable::yourfield ]
Only problem using this exact script would be if the 1st record's team field is empty.
I'd use an update loop that runs immediately after the import:
Go To Record [first]
If [ Not IsEmpty ( YourTable::YourTeamField ) ]
Set Variable [ $Team ; Value : YourTable::YourTeamField ]
Set Field [YourTable::YourTeamField ; $Team]
Go To Record/request/page [next, exit after last]