Four weeks into the 2016 season, the Astros looked like they'd made one of the dumbest trades in recent major league history.

Vince Velasquez, a then-23-year-old right-hander traded away over the winter, looked like he was developing into a star. He fired 15 straight shutout innings to start the season, capping that two-start rampage with a 16-strikeout, no-walk, three-hit shutout of the Padres, one of the most electrifying performances by any pitcher this season. With Houston giving up four other young players in the trade, you could sense the Erik Bedard-trade comparisons coming down the pike, and the horrible regret the Astros might feel for years to come.

That was doubly true given how terribly the pitcher Houston had acquired for Velasquez-and-friends was pitching. Ken Giles had established himself as one of the best relievers in baseball in his first two seasons with the Phillies. But he completely imploded in his first few outings as an Astro. First, Giles got strafed during spring training, so much so that he lost his would-be closer role to Luke Gregerson. In his first four appearances of the regular season, Giles surrendered five runs, serving up three homers. He then gave up another five runs on nine hits in his last four outings in April.

His ERA as the calendar flipped to May? 9.00.

Ken Giles got off to a very slow start in Houston this year. USATSI

That version of Giles now looks like a distant memory. In early May, Giles corrected a mechanical flaw related to his hand placement. That pumped his velocity back to the high-90s, where it had been during his Philly days. The results have been spectacular. Since the start of May, Giles has posted a 2.29 ERA, with 56 strikeouts in 35 1/3 innings. The all-time record for strikeouts in a nine-inning game by a pitcher is 20. Giles just completed a stretch in which he struck out twenty-three batters in nine innings.

Giles' turnaround offers a pointed reminder that we shouldn't overreact to wacky numbers in small sample sizes, even when they happen early in the season, when we don't have anything other current-year data to go on. Players can and do go cold for a few weeks at a time...and we should always be careful not to jump to conclusions.

Giles isn't alone either. Here are four compadres who've shaken off ugly starts to become impact players -- in some cases turning themselves into potential difference makers in playoff races (all stats through Wednesday):

Chase HeadleyAVG.OBPSLG

Headley wasn't just bad in the first month of the season...he was alone-on-a-mountaintop-of-trash awful. The Yankees third baseman was the only qualifying hitter in the majors to produce zero extra-base hits in April. He hasn't quite been Barry Bonds since then, of course. Still, take away April and you have better-than-league-average offensive numbers for the 32-year-old. Add Headley's ability to shake off last year's out-of-character poor defensive season and become a top-10 defender at third base again this year, and Headley could be an actual asset to the Yankees for the two-plus years he has left on his contract...assuming those post-April numbers match his true ability level.

April:37 2/3328475.50
Since:77 2/36514642.78

The Diamondbacks are probably going to regret the six-year, $206.5 million contract they gave Greinke, because the track record of big-money, long-term deals given to pitchers in their 30s is basically baseball Chernobyl. That's not to say that the D-Backs don't have an excellent pitcher on their hands, though. Greinke showed off his trademark strike-zone pounding skills in April, but a combination of a few poorly-located pitches and some bad luck on balls in play turned him into a punching bag for opposing hitters. Those early problems are no more, and Greinke's been a top-10 NL pitcher since then, something we should continue to expect for at least part of his remaining megadeal.

Since:32 2/34713182.48

One of the most prolific strikeout-artist relievers in the game has taken his bat-missing ways to another level since his bumpy first month in Atlanta, whiffing nearly 37% of the batters he's faced since May 1. A two-pitch pitcher, Grilli's slider has been absolutely evil lately: Opponents batted .083 against it in June, and haven't managed even a single hit against it since the start of July. Grilli is the product of one of several in-season moves made by the Blue Jays that didn't look all that exciting at the time, but have since added up to big results.

Dylan BundyIPKBBH

You could argue that no player will make a bigger impact on his team's playoff hopes the rest of the way than will Bundy. For most of the season, the Orioles' rotation consisted of Chris Tillman and pray for rain (with occasional decent outings thrown in by Kevin Gausman). But Bundy has turned on the afterburners since joining the rotation, with some downright incredible numbers over his part four starts in particular: 29 strikeouts, three walks, and a 1.90 ERA in 23.2 innings. Bundy spending most of the season in the bullpen means his innings count isn't a concern for the O's, which is huge news. With the Jays chasing down the O's for first, Baltimore's alternatives for much of the season consisting of human pinatas like Ubaldo Jimenez, and the rotation being the only major weakness on a team with a powerful offense and a formidable bullpen, Bundy could win a legion of fans-for-life in Charm City with a big finishing kick over these next seven weeks.

Thanks to TruMedia for contributing research help for this article.