It's the final countdown.

Friday of this week, the calendar turns itself over to September, which means football starts and pennant races really heat up.

Can it really have flown by that fast? Yup. And that means if you are going to make some moves in your fantasy baseball league, you need to make them now.

Here are two bats and three arms to target on the waiver wire. All players listed are owned in less than 50.0% of ESPN leagues.

Luke Weaver - St. Louis Cardinals (SP)

ESPN Percentage Owned: 30.8%

Sometimes performance dictates that you earn a shot at a major role. Sometimes poor performance by others or injury (or both) earns you a shot -- like in the Wally Pipp case. For Luke Weaver of the St. Louis Cardinals, one could argue he's earned a shot in the rotation, but Adam Wainwright's performance and injury have forced the Cards' hand.

After a cup of joe last year -- 36 1/3 innings pitched in which he whiffed 27.0% of hitters and racked up a 3.55 SIERA -- Weaver entered spring training with a shot at the rotation, but the Cardinals just didn't have room for him.

But with Wainwright hitting the disabled list, Weaver has stepped in to assume his vacated spot in the rotation. And if Weaver's Triple-A numbers are any indicator, he should be up to the task. In Triple-A in 2017, Weaver went 10-2 over 15 starts, posting a 2.55 ERA, 24.9% strikeout rate and 6.2% walk rate.

Last week, in his third MLB start of the year, Weaver fanned 10 over seven shutout innings, He now has 59 2/3 big-league frames under his belt, and he's recorded a 9.8% swinging-strike rate over those innings. With a secure spot in the rotation for the time being, Weaver can be a sweet pickup down the stretch.

Mike Montgomery - Chicago Cubs (SP)

ESPN Percentage Owned: 17.1%

If you're struggling to figure out why the Chicago Cubs haven't run away with the National League Central, look no further than their starting rotation.

In 2016, the Cubs starting pitchers recorded the best ERA (2.96) in baseball, and if you prefer a more advanced metric like FIP, they checked in fourth overall (3.72). In 2017, the numbers are much more telling. The Cubs rank a still-respectable 10th in ERA, albeit over a run higher (4.27), and they check in 10th in FIP (4.28). While those certainly aren't bad marks, they aren't nearly as impressive as what they did a year ago.

Citing shoulder fatigue and needing to shut down things for a bit, Jon Lester exited the rotation and in came Mike Montgomery. The southpaw has shuffled between starting and relief roles this year, but if his last start is any indicator, he could be a major boost to fantasy staffs.

In his first turn as an injury replacement, Montgomery fired six scoreless innings, and he did it in a tough pitching environment in Great American Ball Park against the Cincinnati Reds. If Weaver doesn't work out, or you need another add to your pitching staffs, take a look at Montgomery, who is slated to start twice this week.

Delino Deshields Jr. - Texas Rangers (OF)

ESPN Percentage Owned: 16.1%

Speeds kills -- in more ways than one. Making up ground in the speed category can be really tough to do in fantasy, especially with only a month left. But if you're desperate for those stolen bases, check out Delino DeShields Jr.

Even with only 319 plate appearances to his name, Deshields has swiped 25 bags on the year. Why does that matter? Deshields ranks ninth so far this season in steals overall. For a dude not seeing regular playing time, that's pretty darn good. If there's one thing this dude can do, it's fly on the base paths.

Deshields has been locked into the leadoff spot for the Texas Rangers quite a bit recently. Check out the speedy outfielder to give your roster some assistance in the steals department.

Greg Bird - New York Yankees (1B)

ESPN Percentage Owned: 13.1%

Stop me if you've heard this one before -- a young New York Yankees slugger is absolutely crushing monster homers. Ring a bell?

Instead of discussing wunderkid Aaron Judge, let's discuss the up-and-down 2017 for first baseman Greg Bird, who has been limited to 77 plate appearances. Beset by a nagging ankle injury and then dealing with further complications from the issue, which also cost him all of 2016, this year hasn't gone exactly as planned.

But dude has pop for days, and he appears to be on his way to making a full recovery. If you're having trouble remembering Bird's exploits, over 178 plate appearances in 2015, Bird jacked 11 homers with a .268 ISO, and a very strong 10.7% walk rate.

Bird started playing again in mid-August, and he immediately showcased his power. In 59 Triple-A plate appearances, he posted a .277 ISO and actually walked more than he struck out. He has since been called up to the bigs, although he isn't a regular in the lineup as of now.

For a sneaky power addition, don't sleep on the Yankees' first baseman.

Juan Minaya - Chicago White Sox (RP)

ESPN Percentage Owned: 10.1%

For one final arm to investigate, newly minted closer Juan Minaya of the Chicago White Sox deserves some serious attention.

After Tyler Clippard was traded to shore up the Houston Astros' bullpen situation, the back end of the White Sox bullpen became even more of a mess, but flamethrower Minaya has posted some pretty serious peripherals and may be in line for a big role the rest of the way.

Over 34 innings pitched, Minaya has struck out 30.2% of hitters, and his slider is basically a wipeout pitch. Per Brooks Baseball, Minaya's thrown the slider 61 times the last two months, and he has not allowed a base hit off of it.

With three saves to his name -- all coming after the Clippard trade -- and some nasty weapons at his disposal, consider adding Minaya to your bullpen arms.