The Blues began their defence against the Foxes on Sunday, but only had one goal to show in a laboured first half.
After the break, the holders looked much more their normal selves, adding another four goals to run out 5-0 winners.
READ: City thrash Foxes: Match report
“I thought first half we were a bit sluggish, but that’s natural when you make so many changes and players haven’t played a lot of football through preseason,” said Cushing.
“I thought as the game went on, we got stronger and stronger and it was a good performance in the end.
“It was an important to rest players who have played a lot of football but also to give players minutes, like Tyler Toland, Jess Park and Matilde Fidalgo, to get them into the rhythm of the way we play because they’re new and haven’t played a lot of football with us.
“I always struggle between form and freshness. When you change the team, you can sometimes derail the form a little bit because the likes of Tessa Wullaert, Jill Scott, Demi Stokes and Aoife Mannion are all in form and playing well and contributing to us winning games.
“But we have to keep them fresh and we have to get the likes of Matilde Fidalgo, Tyler Toland, Jess Parks and Laura Coombs into the team because they’re good enough and they’re training well and also because at some point they’ll be needed to play three, four, five back to back games.
“Freshness is key because we want to be competitive on all four fronts.”
Cushing also praised in-form striker Pauline Bremmer who bagged another couple of goals against Leicester.
The German has now bagged six goals in three games and the City boss believes she can do even better.
“I thought she was probably a bit scruffy in the first half,” he said.
“She ran a bit too early and was offside a few times and she was disappointed with that. She took her chances in the second half with another two goals.
“She’s on fire at the minute and we’ll keep her in and keep her scoring goals.”
