You always want to make a good first impression.

Last year, Zack Greinke was The New Guy. The Arizona Diamondbacks had signed the ace right-hander to a six-year, $206.5 million deal, one of the richest contracts ever handed out to a pitcher. At the time, it made sense for the DBacks to go after a pitcher like Greinke. They boasted one of the better collection of position players in the National League, but were in desperate need of an ace.

And by the end of the 2015 season, there were few pitchers in baseball who were as good as Greinke. In 12 big league seasons, he had posted a career ERA of 3.35 while averaging 8.9 strikeouts and just 2.2 walks per nine innings. He had logged 323 career starts and compiled an ERA+ of 122, meaning he was 22% better than a league-average pitcher over that long stretch.

Up to that point, 2015 was his best season as a pro. In 32 starts for the Los Angeles Dodgers, he went 19-3 and led the NL in ERA (1.66), ERA+ (222), and WHIP (0.84). But then 2016 happened.

In his first season with Arizona, he struggled. His ERA of 4.37 was the second highest of his career, the highest being his 2005 season, in which, as a 21-year-old, he posted a 5.80 ERA and lost a league-high 17 games for the Kansas City Royals. His strikeout rate dropped from 23.7% to 20.1%, and his walk rate jumped from 4.7% to 6.2%. He also was far more susceptible to the gopher ball -- after allowing just 14 with L.A. in '15, he surrendered 23 last year.

Thankfully for the D-Backs, 2017 has been a different story, as evidenced by last night's near no-hitter against the Pittsburgh Pirates.

Greinke threw seven hitless innings -- the longest no-hit bid of his career -- before it was broken up by a Gregory Polanco home run in the eighth. He still managed to allow just 1 run on 1 hit in 8 dominant innings, which included 11 strikeouts and 1 walk. After that performance, his ERA dropped to 2.79, with his fielding independent pitching (FIP) settling in at 3.06.

And last night, Greinke's slider was magical.

He generated 13 swings and misses on the pitch, but his fastball was also on point.

It's clear that, even as Greinke has lost velocity on his fastball, his 2016 numbers appear to have been an outlier.

One big change Greinke has made this year was using his slider more and his changeup less.

Slightly more than 27% of Greinke's pitches have been sliders this year, which would be a single-season career high. It also appears that his significant drop in the usage of his changeup has been working out quite nicely -- Greinke's overall 13.5% swinging-strike rate would be the best one he's ever produced in a single season if it's sustained through the next few months.

The below graph shows whiffs per pitch, according to Brooks Baseball -- and these numbers don't even account for Thursday's masterful outing. The change in his repertoire has made all of his stuff a bit better.

Folks, Zack Greinke is back, and that's great news for Arizona -- they're 20-16 and treading water as the NL West's third-place team, and just three games behind the division-leading Colorado Rockies. Even if they're in contention this summer, it wouldn't be surprising to see Greinke's name involved in trade rumors because his contract is massive.

Whatever the front office decides to do, having an effective Greinke is vital to the DBacks' ability to right a ship that's been teetering for the last two seasons.