"Tammy had a bit of a rough time because twice he was substituted at half-time for tactical changes," said Tuchel.
"So he could not have the impact that he demands from himself, we wish from him and he can clearly give for us.
"Then he got injured and the squad played very well without him. Now suddenly we enter the decisive part of the season where it's not so easy to bring players who were injured into the shape or to let them play."
"But it's on Tammy to do everything to make it impossible to leave him out," he added. "It's very, very hard to select the 18 players for Premier League matches."
"In the offensive positions it's always possible to have a huge impact in only some minutes," he said.
"And nothing has changed. We demand a lot of Tammy and he demands a lot of himself, and he is using every minute to convince us he needs to be on the pitch. And so we go on.
"Hopefully he stays fit and will play a key role in the end of the season."