Fantasy Baseball Waiver Wire Adds: Week 21

For most season-long fantasy leagues, this is crunch time.

The last week in August is typically the one in which fantasy leagues decide their championships. With MLB roster expansion coming in September, regulars on losing teams lose playing time to some of the many minor league call-ups who make their appearance, muddying the waters in fantasy quite a bit.

So, in all likelihood, this is your championship week. And if it is, here are a few fantasy waiver wire additions that could make the difference between being the bridesmaid or being the bride.

Yulieski Gurriel - Houston Astros (OF)

ESPN Percentage Owned: 14.8%

Yulieski Gurriel made his Major League debut on Sunday, although it was a bit short-lived. He was pulled from the lineup after three at-bats after straining his hamstring. The 32-year-old Cuban import says he could be ready to play Monday, but it's possible he might miss a game or two this week.

That's not ideal when you consider this is likely the last week in most fantasy leagues. That being said, if Gurriel is in the lineup, there's a chance the slugging outfielder could help teams desperate for outfield help over the next few days.

Gurriel already connected on his first MLB hit, in his first MLB plate appearance.

Gurriel didn't do much as Houston raced him through four levels of minor league play, accumulating just 15 games and 61 plate appearances. He batted .250/.262/.429 with 2 homers. He struck out 15 times and walked twice.

His pedigree in the Cuban professional league implies a high on-base, high-power player, so this would be an upside, roll-the-dice type of play.

Dansby Swanson - Atlanta Braves (SS)

ESPN Percentage Owned: 20.9%

The number-one overall pick in 2015, Dansby Swanson has arrived to the Majors quite rapidly. Since being acquired from the Arizona Diamondbacks last year in the ill-fated Shelby Miller deal, Swanson has made the jump from AA right to the Majors.

In 84 games (377 plate appearances) in AA, Swanson hit .261/.342/.402 with 8 homers, 45 RBI, and 6 stolen bases. He hits the ball hard and has some speed on the bases, and he should get a solid amount of playing time for the rest of the season.

Swanson has a ton of talent and may prove useful to teams here in the final week of August.

Jedd Gyorko - St. Louis Cardinals (IF)

ESPN Percentage Owned: 32.3%

Jedd Gyorko has quietly put together a solid power season for a middle infielder and offers positional flexibility that makes him an even more valued commodity, eligible at all four infield positions.

In 293 plate appearances, Gyorko has batted .246/.309/.496 with 20 home runs and 44 RBI -- solid pop from a middle infielder. He leads all National League hitters with 13 home runs in the second half of the season and continues to be a force in limited plate appearances this year.

David Phelps - Miami Marlins (SP/RP)

ESPN Percentage Owned: 24.2%

Miami's David Phelps is making the transition from outstanding relief pitcher to outstanding starting pitcher and so far has made the jump with great aplomb.

Overall this season, Phelps has a 2.28 ERA and is striking out 11.4 batters per nine innings this season, mostly as a reliever. But in four starts (20 2/3 innings), Phelps has a 1.31 ERA and has struck out 11.32 batters per nine innings, with 26 strikeouts and 7 walks.

He's also a relief pitcher who will start games, something which could be valuable if you are otherwise strong at closer.

Robbie Ray - Arizona Diamondbacks (SP)

ESPN Percentage Owned: 31.9%

Arizona left-hander Robbie Ray has a 4.31 ERA in 140 innings so far this season but has been looking particularly good recently.

Over his last six starts, Ray has a 3.79 ERA and has seen his strikeout rate explode to 13.12 strikeouts per nine innings, striking out 52 and walking just 8. And in his last three starts, he's given up just 2 earned runs in 19 innings pitched.

He seems to be hitting his stride just in time for championship fantasy week.