The trade: The Houston Astros acquired closer Ken Giles from the Philadelphia Phillies for right-hander Vincent Velasquez, left-hander Brett Oberholtzer, and a third player, believed to be minor league outfielder Derek Fisher.

Even though Giles has five seasons left of team control, the rebuilding Phillies decided to sell high on their young closer and got a nice return of talent. Velasquez debuted with the Astros in 2015, pitching 55 2/3 innings while starting seven games and pitching 12 times in relief. He posted a 4.37 ERA, but had a 3.46 FIP and held opponents to a .240 average, solid results for a kid who hadn't pitched above A ball before 2015. While he's battled injuries in the minors, he possesses a nice fastball/curveball/changeup repertoire, averaging 94.5 miles per hour on his fastball and touching 99 in relief. I'd let him start for now but he has the stuff to be an impact reliever.

Oberholtzer is a 26-year-old lefty with 42 career major league starts. Lacking anything resembling a knockout pitch, he's a fringe rotation candidate, which means he's likely the Phillies' No. 2 starter.

Fisher was the 37th pick in the 2014 draft, an outfielder from the University of Virginia. He hit .275/.364/.483 in Class A, most of that coming at Lancaster, where everyone hits, so let's see how his bat plays at the upper levels.

Meanwhile, the Astros got a 25-year-old with a career 1.56 ERA in 115 2/3 innings. That's a little misleading, however, as he allowed nine unearned runs in posting a 1.80 ERA in 2015. Of note: His K rate decreased and his walk rate increased from his 2014 debut. He's strictly a fastball/slider guy, although that hasn't resulted in any platoon split so far, even with a much higher strikeout rate against right-handers. He's a good reliever, but the small steps backward in 2015 are a little concerning for his long-term dominance.

The reason: Why give up a big haul for a reliever? Well, you might remember Game 4 of the Division Series, when the Astros blew a 6-2 lead in the eighth inning against the Kansas City Royals, who won 9-6 and then took Game 5. If the Astros relievers protect that four-run lead we have a different World Series champ and a different view of what it takes to win a World Series.

While the Houston bullpen was excellent in the regular season, that inning highlighted the need for a power arm -- or maybe it was just one bad game at the wrong moment and this trade is an overreaction. The Astros ranked sixth in the majors with a 3.27 bullpen ERA, third in strikeout rate and second in wOBA allowed ... but last in average fastball velocity, with closer Luke Gregerson averaging just 89.2 mph on his fastball.

The impact: Obviously, the Astros are hoping they've acquired an elite closer. Have they? Giles' ranks among 132 relievers who pitched at least 50 innings:

ERA: 6th

wOBA allowed: 27th

Batting average: 47th

K rate: 22nd

BB rate: 84th

HR rate: 3rd

I certainly wouldn't classify him as a top-10 reliever, primarily due to the questionable command. He has allowed limited home runs so far in his career, and maybe that batting average allowed improves with better defense behind him.

The bigger picture related to this is interesting:

I like Ken Giles, but you can make another one. Getting Vincent Velasquez-plus for him is beautiful. #phillies

— Joe Sheehan (@joe_sheehan) December 10, 2015

Here's another fun one... #Astros have thrown 29 pitches 99 MPH+ since 2008. Ken Giles did it 37 times last year.

— Daren Willman (@darenw) December 10, 2015

The old saw about bullpens from sabermetricians and many general managers echoes Sheehan's tweet: Don't pay big for relievers, either in money or talent, because they're relatively easy to find. As Joe pointed out, just two years ago Giles had a 6.63 ERA in the Florida State League.

Yet this offseason we've seen this trade; the Red Sox gave up premium talent to acquire Craig Kimbrel and Carson Smith; we've seen the Dodgers nearly acquire Aroldis Chapman although they already have a top closer in Kenley Jansen; we've seen the small-market A's sign Ryan Madson to a three-year, $22 million contract even though he's pitched just one season in the past four AND sign John Axford, he of the 4.23 ERA over the past four seasons, for $10 million over two years; we've seen the Tigers trade for Francisco Rodriguez and Justin Wilson and sign Mark Lowe, who topped 50 innings for the first time since 2009, for $11 million over two years; the Cubs gave Trevor Cahill, picked up off the scrap heap in August, $4.25 million; the Orioles need a starting pitcher but instead have only re-signed reliever Darren O'Day for $31 million; the Royals gave $25 million to Joakim Soria, coming off his first good season in several years.

So what's going on? It's probably too easy to say everyone is just looking to copy the Royals and build a dominant bullpen trio or foursome, but it seems like that's what's going on. Teams are certainly adopting to the fact that starting pitching is very expensive to acquire, so building a deeper bullpen eases the demand needed from your starters. And it's no longer just about building a strong regular-season team and hoping things go your way in October but building a team that works in the postseason, where you can give a higher percentage of your innings to a few key relievers due to all the off days.

In the Royals' case, Greg Holland was a late-round pick who developed; Wade Davis actually flamed out as a starter; Kelvin Herrera was groomed in the minors as a reliever; Luke Hochevar was an even bigger flop as a starter than Davis. In many ways, the Royals lucked into their bullpen.

But if the Royals lucked into their pen, other teams may have to spend build their late-inning trio. Are relievers that easy to find? Well, yes ... and no.

In 2015, 59 relievers pitched at least 50 innings with an ERA of 3.00 or under.

In 2014, there were 67 such relievers.

In 2013, there were 65 such relievers.

The number of relievers who did this in two of those three seasons? Forty.

The number who did this in all three? Just 12. Relievers burn quickly; very few are dominant year after year after year. The Astros believe they've acquired one of those few in Giles, preferring to bet on him rather than Velasquez's less-known future.

Was it worth it? Check back in October.