Lee, who has never been on the DL in his career, will have surgery to repair the fracture on Monday around 1 p.m. CT. Team doctor Tom Mehlhoff will perform the procedure.
After the Astros' 3-1 win over the Reds, Lee's eyes welled up a bit as he talked about the injury that ultimately ended his season.
"I've never felt this good in my career at the plate," Lee said. "I believed I was going to help [the team] to make a comeback and do the best for the team but now, I'm out. It's pretty bad. I have to get it operated on and they say six to eight weeks, so probably, I'm out [for the year], unless the guys make a comeback and I'll be back for the playoffs."
Immediately after he was hit on the hand, Lee grimaced and fell to the ground, where he was tended to by head athletic trainer Dave Labossiere. As Lee stood up and walked off the field, cameras captured a close-up shot of the little finger on his left hand, which was dripping with blood.
"I knew it right away that it was not going to be good," Lee said. It hit me square."
Lee did not place any blame on Arroyo, whose 2-2 fastball crushed Lee's finger.
"He was trying to go up and in," Lee said. "I couldn't get out of the way. I'm a hitter that attacks the ball -- I don't wait back. I saw it coming, and I tried to get out of the way, but the ball's coming in pretty good."
The injury occurred one day after Lee logged his 100th RBI of the season and the 1,000th and 1,001st of his career. The loss of Lee could have lasting effects on the Astros, who have won 11 of their last 15 games but are still considered a long shot to make the postseason.
It's difficult to imagine the Astros will have enough offensive power to make a playoff push without Lee, who was hitting .314 with a team-leading 28 homers at the time of the injury.
"With men in scoring position, he's just been an awesome player," Cooper said. "Getting big hit after big hit. He's carried us over the last month and a half or so with home runs, base hits, and he's played terrific defensively. It's a big hole to fill."
Darin Erstad will receive the majority of the starts in left in Lee's absence, but Abercrombie could see playing time there as well, and Cooper mentioned Ty Wigginton as an outfield candidate, too.
"That's a tough one," Miguel Tejada said. "To lose a guy from your team is hard. But Carlos is a guy who has been, in the last month or two, carrying this team. We felt like we had a chance. Now we lose one of the best hitters on the team, and it's hard.
"I'm sorry for him, because I think this year could have been one of the best years of his life. It's not good."