Cleft or Inversion? It Was the Team That … (C1 Grammar)

Use It was / is + the spotlighted person or thing + that to answer "which one?" and pin down the doer.

It was X that ... — spotlight who did it

Never / Rarely / Seldom at the front — then the swap

Fronting Never, Rarely, Seldom or Little is formal and emphatic, and the helping verb then comes before the subject.