It's waiver time. One of the keys to any fantasy success is not only nailing your draft, but scouring that waiver wire for players who can give your team a boost. Even though fantasy baseball can be a really long season, it's key to search those waivers and take it week-by-week to cement your fantasy status.

The four players below are all owned in fewer than 50% of Yahoo leagues and could give your team a lift.

Mark Melancon - San Francisco Giants (RP)

Yahoo Ownership: 21%

It's time to take another fun spin on the closer carousel, and this time, we at least have a guy who has done the job before -- Mark Melancon will take over ninth inning duties for the Atlanta Braves, and with the Braves being one of baseball's best teams, Melancon is now a commodity we have to pay attention to.

Melancon has always shown solid peripherals, but he does not have elite stuff for a closer. He boasts a 23.1% strikeout rate, a middling 8.2% walk rate, and a 10.4% swinging-strike rate.

But with Shane Greene struggling mightily, and the Braves already racking up 69 wins so far this year, opportunities should be plentiful for Melancon. He needs to be owned in way more leagues than 21%.

Vince Velasquez - Philadelphia Phillies (SP)

Yahoo Ownership: 26%

Look, if you want to stop reading this article immediately because I recommended Vince Velasquez, I really can't blame you. All of us have probably both owned and been majorly disappointed by the mercurial right-hander.

While he has great swing-and-miss stuff, Velasquez often buries your teams. This year alone he has a 4.23 ERA over 78 2/3 innings pitched, a year after he recorded a 4.85 ERA over 146 2/3 innings pitched.

But something may have finally clicked for Velasquez over the last few weeks -- since rejoining the starting rotation back on June 16th, VV has fired 39 innings with a 26.9% strikeout rate. Perhaps most importantly, he's got a gorgeous 6.3% walk rate in that span. Walks, long his bugaboo, may finally be getting curbed.

And while he is still prone to the long ball -- he has allowed 1.85 home runs per nine innings pitched over that same stretch -- they hurt a lot less when he hasn't walked the bases loaded. For a rotation desperately needing a shot in the arm -- both the Philadelphia Phillies and your fantasy team -- Velasquez could be a major add.

Aristides Aquino - Cincinnati Reds (OF)

Yahoo Ownership: 45%

So if you don't know who Aristides Aquino is, let me get ya up to speed real quick.

The young slugger has mashed taters at literally every level -- including the bigs. Over 323 Triple-A appearances this season, all he did was hammer a cool 28 home runs en route to a sizzling .337 isolated power (ISO) mark. That's after he slammed a combined 60 dingers in his last three minor league seasons.

While the sample size is small, Aquino has already ripped four home runs in 25 plate appearances for the Cincinnati Reds, and he is often manning the fourth or fifth spot in the lineup.

If you need some pop down the stretch, peep Aquino.

Dinelson Lamet - San Diego Padres (SP)

Yahoo Ownership: 24%

If you've ever fathomed how hard it is to hit a major league baseball, watch Dinelson Lamet's slider in action:

The name may ring a few bells, as Lamet was an up-and-comer in the San Diego Padres' organization before suffering an arm injury and missing all of the 2018 season as well as a major chunk of the 2019 season. But he is now back, and hell hath no fury like Dinelson Lamet.

Over 30 innings this year, Lamet has posted a crisp 32.6% strikeout rate and 14.1% swinging-strike rate. His control and command continue to be an issue as he's issued free passes 10.1% of the time.

The fellas over at The Pitcher List have coined the term "money pitch." To qualify as one, a pitch has to generate an out-of-zone swing rate (O-Swing Rate) greater than 40%, an in-the-zone rate greater than 40%, and a swinging-strike rate better than 15%. In short, it's a dominant pitch that does it all, and Lamet's slider is nearly that with a 40.3% O-Swing Rate, a whopping 25.6% swinging-strike rate, and a 38.3% in-the-zone rate.

If Lamet can curb the walks, he clearly has some big-time upside, and he can be a major weapon for your fantasy staffs, especially as the fantasy playoffs begin later this month. Even if he can't get his free passes under control, he's more than just a streamer at this point.