"Compliment to Ottawa, they used their opportunities," Krueger said. "We took four offensive-zone penalties, unacceptable, and their power play just killed us."
The loss opened a 10-game stretch featuring nine games in KeyBank Center, where the Sabres were 14-5-3 entering the night. They were also coming off a 10-day break between games, while the Senators played Monday against New Jersey.
Krueger said prior to the game that he expected his team to have to weather an early adjustment period. Beyond that, he felt they would be able to use their energy to their advantage. That energy only showed in spurts.
"We had difficulty finding our legs and then for some strange reason, once we found them, we kept going in and out of the game," Krueger said. "We seemed to be in it, and then we fell back, we went it, and we fell back, and it just went that way all the way.
"We never really got a rhythm, or we never felt the Sabres hockey we want to play. So, it's very frustrating. But compliment to Ottawa for the way they played here today. They played hard, they played well, and they used their opportunity."
Entering the night, the Sabres saw the long stretch of home games as an opportunity to make up ground in the playoff race. They sit 10 points out of both the second wild card in the Eastern Conference and third in the Atlantic Division.
Disappointing as the result was - due to the result and Ullmark's injury - they still see that opportunity moving forward.
"If one game throws everything off kilter we don't have much of a foundation," Krueger said. "We feel we do. We feel a group that has truly bought into a process we had an off game coming off the break here.
"Ottawa did a hell of a job here on their back-to-back using the game from yesterday and we should have had more energy in the second half. We didn't have it, but there is full belief in that room of the way we're going here and adversity is something you need to look in the eyes and you need to be strong about. You need to use it, and that's what we'll do here. We got two days to get ready for Montreal and we will be ready."