The Arizona Diamondbacks shocked the baseball world by landing free-agent ace Zack Greinke on Friday night. With it, there are several reasons to believe that the Diamondbacks are going to be a contender in the NL West next season. Let's run them down, shall we?

First off, did you know the Diamondbacks had one of the best offenses in the NL last season? For real, they did. I tried to tell everyone who would listen in the weekly power rankings, but they just kept flying under the radar. They ended the season with 720 runs scored, only trailing the Rockies among NL teams.

It wasn't a fluke, either. The Diamondbacks were second in batting average, third in on-base percentage, second in slugging percentage, first in hits, third in doubles and second in triples in the NL. This team can hit, and there's every reason to believe it will continue, given how young the lineup is.

As things stand, MVP contender Paul Goldschmidt is 28 while A.J. Pollock (who finished 14th in NL MVP voting and should have been higher) is turning 28 on Saturday. Those are the anchors, but they aren't alone.

Ender Inciarte will be 25 next year and is coming off a very good season. Converted pitcher David Peralta not only has one of baseball's best stories, but he had a major breakout last season at age 27. Sweet-swinging Jake Lamb has big upside and will be 25 next year and Welington Castillo found his power stroke once acquired.

Not one expected regular starter will be as old as 30.

Further, the D-Backs can absolutely pick it. Per defensive runs saved (DRS), Arizona was the NL version of the Royals. Seriously. They saved 71 runs last season as a team. Second in the NL was the Marlins at 37. In fact, the D-Backs were best in the majors and the Royals were second at 56.

That's mostly thanks to Goldschmidt, Pollock, Enciarte -- all excellent defenders -- and shortstop extraordinaire Nick Ahmed, but the team as a whole is incredible defensively.

So why didn't they win more than 79 games?

Superstars Zack Greinke and Paul Goldschmidt lead a fun D-Backs team.
Superstars Zack Greinke and Paul Goldschmidt lead a fun D-Backs team. (USATSI)

Because the pitching was awful.

The D-Backs ranked 11th in rotation ERA at 4.37 last season. And get this: The five NL playoff teams were the ones that ranked 1-5 in rotation ERA (in order: Cardinals, Dodgers, Cubs, Mets, Pirates).

The rotation was especially terrible before the All-Star break, as it posted a 4.66 ERA in the first half.

It was already likely to be better for 2016, as Patrick Corbin is now fully back from Tommy John surgery. He made 16 starts last season, posting a 113 ERA+ and 8.3 K/9. For now (we'll get to what I mean in a second), he's the No. 2 behind Greinke.

There's also 23-year-old prospect Archie Bradley. He's only made eight big-league starts, but after dealing with injuries, a healthy 2016 season could mean a breakout. He has the ability to take several steps forward in one season, which is why he was once the seventh-overall pick in the draft and has consistently been ranked as one of baseball's top prospects.

And what if the Snakes aren't done? There's this on free agent Mike Leake:

Think they're tapped out with Greinke making more than $30 million a year? Think again.

What the D-Backs have on the books isn't much in baseball money. Before the Greinke signing, the Diamondbacks looked to only have a little more than $60 million in payroll for next season, thanks to mostly young players and Goldschmidt having an unbelievably club-friendly deal (five years, $32.05M).

So let's run that above $90 million. OK. Arizona isn't a small market and the D-Backs signed a huge TV deal in the spring. How huge? Only a little more than $1.5 billion over the course of 20 years. This isn't how it works, but that's $75 million a year. The team can afford to go significantly higher than $90 million in payroll for next season.

Put simply: If they wanted to, the D-Backs could probably even go nuts for Johnny Cueto.

If they land Leake, a Greinke, Leake, Corbin top three with some combination of Bradley, Robbie Ray, and Rubby De La Rosa in the rotation is fine, considering the offense and defense.

With the young position players who can both rake and pick it -- yard work guys, apparently -- in addition to the spending power, this has the look of a proverbial sleeping giant that decided to wake up with the Greinke signing. Keep in mind, they hovered around .500 all year despite having a terrible rotation.

Yes, the bullpen could use some shoring up, but it's only Dec. 4. There's still plenty of time to address that.

One of the NL's best offensive and defensive teams just added one of the league's best starting pitchers and can add more. If you aren't taking them seriously yet, you better start. These Snakes are starting to look a bit scary.