This is the fifth of a six-part Around the Horn series that will take a position-by-position look at the Astros' projected starters and backup options heading into next season. Up next: Relief pitching.
HOUSTON -- The Astros' glaring need for a power arm in the back of the bullpen was the top priority of the offseason for general manager Jeff Luhnow, who pulled off a major deal at the Winter Meetings to get closer Ken Giles from the Phillies in exchange for four players.
The price for landing the 25-year-old Giles, who has a 100-mph fastball, was steep. Among the players the Astros sent to Philadelphia were former No. 1 pick Mark Appel and hard-throwing youngster Vincent Velasquez, but in Giles the Astros got a player they can control for five years with major upside.

Giles joins a bullpen that ranked fourth in the American League last year with a 3.27 ERA, and that was after a rough September in which it allowed 85 hits in 76 2/3 innings and had a 5.63 ERA. Things didn't go better in the playoffs, when Astros relievers posted a 6.23 ERA in six games, blowing a late lead against the Royals in the decisive fifth game of the AL Division Series.
At some point in the spring, the Astros will likely announce Giles as their closer, which is the reason they got him. He had a 1.80 ERA and 15 saves in 17 opportunities as the Phillies' closer in 2015. In 20 combined appearances in August and September, Giles posted a 1.21 ERA with 27 strikeouts in 22 1/3 innings pitched, with a .159 opponents' batting average.
• Around the Horn:Starting pitching | Outfield | Infield | Catchers
Giles will join a deep and veteran bullpen that includes right-handers Luke Gregerson, Pat Neshek, Will Harris and Josh Fields, and left-hander Tony Sipp, who signed a three-year deal in December to return.
"We've got the chance to have an exceptional bullpen this year," Luhnow said. "Last year, our bullpen was good -- among the best in the American League most of the year and overall. But with the addition of Giles and some of the guys that could potentially mix and match, we feel like we've got enough options and enough different looks to help us win those games we need to win."
Gregerson did a solid job as closer last year, saving 31 of 36 games while going 7-3 with a 3.10 ERA. He's durable with a long track record of success, and he should slide into the eighth-inning role without any problems. Harris, claimed off waivers prior to the 2015 season, was a find. He had a 1.90 ERA and a 0.90 WHIP in 68 appearances and played a bigger role as the season progressed.

Neshek was 3-6 with a 3.62 ERA, but he allowed 13 hits and six earned runs in 6 1/3 innings in September. Neshek underwent offseason surgery for a Jones fracture in his right foot, which hindered him through all of the season.
Sipp parlayed his terrific season into $18 million over the next three years. He started the season as a lefty specialist, but by the second half, he was being used in big spots late in games and against right-handers, who hit .190 against him. He held opponents scoreless in 49 of his 60 appearances.
The Astros could use a second lefty to replace the departed Oliver Perez. They could fill that role from a group that includes Kevin Chapman, Edwar Cabrera or veteran starter Wandy Rodriguez, who's back with Houston on a Minor League deal. The depth of the Astros' rotation could see Mike Fiers or Scott Feldman shifted to the bullpen at some point in a long-relief role.