The Arizona Diamondbacks have gone 19-45 since June 20, including a 6-19 run in July.
They occupy last place in the National League West and are 15 games out of a playoff spot.
"This is something nobody expected," Arenado said. "We didn't expect it to be like this. But it is. There's no running away from it. It is what it is."
Arenado went on to say, "It feels like a rebuild."