Five starts into a five-year deal with the Detroit Tigers, Jordan Zimmermann has a 5-0 record and a 0.55 ERA.
Because the number five is easily associated with Zimmermann as he prepares for his outing Friday night opposite Cole Hamels and the Rangers at Comerica Park, here are five things to know about his historic start to 2016.
1. It is not easily explained.
Let's start with an obvious question: Are there any notable changes that would point to Zimmermann's early results?
"Honestly, nothing," Zimmermann said. "I feel like I'm the same person I've always been."

We knew Zimmermann was good before all of this. From 2011-15, his 3.14 ERA ranked 12th among qualified starters. And we all watched him close out 2014 in style, with a no-hitter against the Marlins.
But Zimmermann has never had a run like this.
Few have.
Since 1969, when the mound was lowered, only two pitchers with a minimum of five starts have gotten through April with a lower ERA than Zimmermann's mark: Fernando Valenzuela (0.20 in 1981 and 0.21 in '85) and Zack Greinke (0.50 in 2009). Valenzuela's '81 effort and Greinke's '09 start each led to a Cy Young Award-winning season.
Zimmermann is using his slider more and his four-seamer less, on average. His four-seam usage has dropped from 62.6 percent with the Nats last year to 55.2 percent this year, and his slider usage is up from 22.2 to 33.3 percent. Those are significant changes. But the sample size is too small to draw meaningful conclusions. In two of Zimmermann's five starts (his home opener outing against Yankees and his April 25 start against the A's), his slider usage was more in line with his career norm. So the numbers are skewed by the more dramatic patterns of the other three starts.

Zimmermann isn't overpowering people. His contact rate (84 percent) is the 10th-highest in the Majors, and his strikeout rate (17.4) and walk rate (5.3) are actually slightly worse than his career norms. But while opponents are hitting .224 off Zimmermann overall, they're batting just .188 with men on and .130 with runners in scoring position. He's stranding 92.3 percent of baserunners, 20 points higher than the league average for starters.
"Luck's just on my side right now," Zimmermann said.
2. It could mean big things for a former teammate.
Zimmermann's five-year, $110 million contract was the first nine-figure deal given to a member of the Tommy John alumni club. Some teams believe the average shelf life of a new ulnar collateral ligament is roughly seven years, so a long-term entanglement with a pitcher who has already accrued post-surgical wear and tear (Zimmermann had his surgery in August 2009) is a risky endeavor, even by long-term pitching contract standards.

It will take the full five years of the deal to make a proper and rational determination on how this worked out, but baseball's free-agent game doesn't take five-year breaks. Zimmermann ushered in a wave of elite arms with elbow scars who will be hitting the open market in the next few years, including Matt Harvey, Jose Fernandez and Yu Darvish. But the most immediate member of the group is Stephen Strasburg, a 2010 Tommy John recipient and pending free agent. If Zimmermann carries this strong start into a strong season, it could embolden a team when it comes time to decide whether Strasburg -- who is also off to a terrific start (5-0, 2.36 ERA) -- is worth not just $100 million but perhaps $200 million.
Zimmermann said there were several teams who considered him untouchable -- at least, in the nine-figure realm -- because of his history.
"Hopefully," he said, "I've changed the minds of a few teams that this Tommy John thing is not a big deal."
3. It has provided balance in the baseball universe.
Twelve other starters have changed teams with contracts valued at more than $100 million (Johan Santana included, because an extension was a requirement of his acceptance of his 2008 trade from the Twins to the Mets). Until Zimmermann, the best early impression by a $100 million arm came just last year, when Max Scherzer went from Detroit to Washington (seven years, $210 million). In his first five starts, he went 1-3 with a 1.26 ERA.
It seems only appropriate that Zimmermann's move from Washington to Detroit would come along and even the cosmic scales.

And while Zimmermann was enjoying the best five-start ERA sample for a nine-figure arm, Greinke (six years, $206.5 million with Arizona) was suffering the worst (2-2, 6.16 ERA in first five starts). So there's another bit of balance. D-backs fans are still waiting for Greinke to come around, but Tigers fans have quickly fallen in love with their new right-hander.
"It just gives them that reassurance," Zimmermann said, "that this is what you got and this is what you're going to have, hopefully, for the next five years."
4. It runs counter to a tried-and-true narrative.
Zimmermann, per the Elias Sports Bureau, is just the fourth pitcher in history to earn a victory in his first five games in the American League -- with its DH-laden lineups -- after having previously pitched in the National League. And the others -- Bill McAfee (2.49), Jerry Koosman (3.86) and Matt Palmer (4.26) -- all did so with substantially higher ERAs. (Koosman was the only one in that group who earned all five victories as a starter, anyway.)

"Honestly, I think it works both ways," Zimmermann said. "Hitters haven't seen me, and I haven't seen any of those guys, so I don't know what their tendencies are. I'm just pitching to my strengths. The more they see me, the more they'll adjust."
Of the 47 individual batters Zimmermann has faced so far this season, 25 had never seen him before and another 14 had only faced him for three or four previous plate appearances -- or the equivalent of one game. So that just leaves eight players who had anything resembling a true "history" against him.
In this case, the unfamiliarity clearly has worked in the pitcher's favor.
5. It has caused clubhouse controversy.
Not genuine controversy. But because self-interest is a natural element of human existence, it only stands to reason that the backstop who caught three of the five starts that earned Zimmermann AL Pitcher of the Month honors would want a piece of the action.
"I don't even need him to say, 'Thank you,'" Jarrod Saltalamacchia joked. "Just give me what I deserve. A Rolex."

Zimmermann is unconvinced.
"Well," he said, "I pitched to three different catchers [James McCann, Bobby Wilson and Saltalamacchia] in five starts, so …"
We'll let the batterymates figure out that issue. The rest of us can just sit back and watch what Mr. 5-0 has in store for start No. 6.