The signing completes the Astros' makeover of the middle of their infield. On Nov. 18, they acquired shortstop Clint Barmes from the Rockies. Hall can earn either $4 million or a $250,000 buyout in 2012.
"Bill brings some additional offensive punch to our lineup," Astros general manager Ed Wade said. "He hit 18 home runs in limited at-bats last year with Boston, and we think our offense is enhanced with the run-producing potential that both he and Clint Barmes can provide.
"Bill's defensive versatility allows us to consider using him a number of different ways, but our plan is to have him play second base regularly. Jeff Keppinger has done a very solid job for us over the past two seasons, and with his versatility, we believe there will be plenty of at-bats to go around."
Second base is where Hall wants to be.
"If you can get a second baseman with power, it puts you ahead of other teams in your division, other teams in your league," Hall said. "Obviously, there are some teams in this division with some really good second basemen with a lot of power. We feel we can match that and win games."
Two days ago, Hall talked to Mills, and naturally, the conversation started with some good-natured jokes about Francona. Hall did his homework on Mills, too.
"Everybody seems to love him to death and says he's a guy you want to play for," Hall said.
The versatile Hall, who turns 31 on Dec. 28, batted .247 with 18 home runs and 46 RBIs in 119 games for the Red Sox last season. Among Major Leaguers with 350 at-bats or fewer, his 18 homers ranked tied for fourth.
Wade wanted to more run production after the team ranked last in the National League in 2010. Astros shortstops and second basemen hit a combined nine homers last season; Hall and Barmes combined for 26.
A few teams offered Hall a chance to play other positions, and a couple wanted him to be their utility player. He doesn't like that label.
"I don't like the words 'utility player' -- I call myself a baseball player," Hall said. "No matter where you put me on the field, I'm going to try to do something special and definitely not embarrass myself.
"I've always said, I'm really good at a lot of positions, but if I concentrated on one, hopefully I could be great. That's my goal going into this season is to become a great second baseman and play as hard as I can. Never worry about hard work. I know what it takes."
Hall was expected to be the Red Sox's utility man last season, but he ended up playing in 119 games and getting nearly 400 plate appearances because of injuries to others. The right-handed hitter played left field (55 games), second base (51), right field (nine), center (seven), shortstop (six) and third (five) for Boston and even pitched one inning on May 28 against the Royals, throwing 11 pitches and getting three groundouts in a 12-5 loss.
Now that he's a full-time second baseman, no more pitching?
"My stock rose because of that pitching performance," he said, laughing. "A lot of teams were calling me because they needed a relief pitcher."
He's joking. But if the Astros need an extra arm, he's ready.
"If they ask me, my answer will always be 'Yes,'" he said.
For his nine-year career -- which saw him spend his first seven-plus years with the Brewers -- Hall is a .250 hitter with a .310 on-base percentage and 122 homers. He has a career .261 average against the NL Central. Of his 940 games in the field, 155 have been played at second base.
Being back in the NL Central also was plus.
"I know what kind of competition there is in this division," Hall said. "For the most part, the teams in this division beat up on each other, and everybody is looking for an edge. ... It's a division I'm comfortable with, and I'm definitely excited to be back in it. I've already circled some dates on the schedule."
Are those games between the Astros and his former team, the Brewers?
"Who knows?" Hall said. "I have some dates circled on my schedule."
Keppinger was the Astros starter at second for much of last season and may return to a utility role if he's not dealt to another team. He hit .288 with six homers, 59 RBIs and a team-high 34 doubles last year after taking the starting job away from Kazuo Matsui, but has limited range and lacks power.
It would seem that Minute Maid Park's cozy left field would favor Hall, but he's aiming for the gaps in right- and left-center.
"Everybody's talking about the Crawford Boxes [in left], but what I'm more excited about is I can go opposite field again," he said. "That was a huge part of my game obviously in 2005, 2006, when I was at my best before injuries made me change some things with my swing. Obviously, I've got that back."
His best season so far was 2006, when Hall hit .270 with 35 homers and 85 RBIs for the Brewers.
There's more to Hall's game than his hitting. He's looking forward to working with some of the young players on the Astros' roster.
"This game is tough and there are a lot of things you can learn and it's not always about baseball," he said. "I'm a guy who had a lot of success, and then due to some things that happened, I didn't have success that I felt I could have. It was a tough point in my life and then I bounced back.
"Being on both sides of the line, I feel I can help guys to make sure they don't go down the wrong path -- and I'm not saying I did, but things happen. No matter who you are, this game isn't always great. You're not going to have a great at-bat every single at-bat. You've got to deal with ups and downs. I've been through a few of those in my career. I want to help this team -- that's my main job, to help this team win on offense and defense."
Which is probably exactly what Francona told Mills.