We're into the final quarter-season of fantasy baseball. Teams are starting to dig deep as they try to get a read on the future of their franchise. Fantasy owners will need to remain nimble. Whether you're a contender or a rebuilder, snagging quality players off the waiver wire is an important part of August and September.

Francisco Mejia watch continues! Since losing his hitting streak last week, Mejia has played four games. He went hitless in two of them, but he still drew walks. He's reached base in 55 straight games.

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Dynasty Advice for Week 21

Dansby Swanson - Atlanta Braves

No self-respecting dynasty league entered 2016 without somebody laying claim to Swanson. It's nice that we'll get a chance to evaluate him on the big stage this fall. His rapid ascension from Double-A to the majors could also present an offseason buying opportunity for savvy owners.

Swanson isn't dripping in plus tools. He lacks game changing power like Trevor Story. He doesn't have extreme plate discipline like Andrew Benintendi. He probably won't hit for a high average like Corey Seager, and he certainly won't run like Trea Turner. Swanson's value proposition is an all-around slightly above average set of tools.

Usually, it takes time for players like Swanson to catch on at the major league level. His future probably looks something like 2016 Anthony Rendon. The ceiling is comparable to 2014 Rendon. Dynasty owners should be ecstatic with either result. Don't expect more than flashes of brilliance before 2017 - if not 2018 or 2019.

Here's where it gets interesting. When Swanson is inevitably mediocre, be the first in line to acquire him. His owner may want to bail on what may suddenly look like a bust risk. In truth, this is how prospects develop. It's chunky, difficult to predict, and takes time. You have to stick with the ones who will eventually succeed. The current iteration of Swanson is very blue chip once he adjusts to major league pitching.

Roman Quinn - Philadelphia Phillies

One of the key indicators for player value is an actual opportunity. Players need to play to get better. Quinn could have a wide-open opportunity in Philadelphia this September. The club only has two must-play outfielders - Odubel Herrera and Aaron Altherr. Quinn is already on the 40-man roster so he's a near lock for a call up.

It feels like Quinn has spent his entire career on the disabled list, but there's no sign the injuries have sapped his speed. In 297 Double-A plate appearances, he has 29 steals. The bigger issue in his game is a penchant for swinging strikes. His inability to stay on the field has led to an inconsistent approach at the plate. If you check out his career numbers, his strikeout rates generally hover around league average. He'd probably spike to somewhere around 25 percent strikeouts if he were called up today (or in 10 days).

Quinn does have some pop - mostly of the doubles variety. In the best case scenario, the Phillies hand him a near-everyday role in September and he posts seven or more stolen bases while supplying Travis Jankowski-like numbers. Quinn possesses elite defensive potential so he doesn't need to mash to provide value to the Phillies. And he only needs to run to provide value to you.

Rapid Fire

Austin Slater - San Francisco Giants

Every week, I try to scrape together a couple outside-the-box targets. Slater is one of those. An advanced feel for hitting and improved physicality have helped the 23-year-old make some noise this summer. Between Double- and Triple-A, he has 13 home runs and eight steals in 407 plate appearances. He has an interesting blend of talents with an ability to hit for average, draw walks, and produce at least some pop.

The Giants converted him from outfield to second base when they drafted him. I don't have any updated reports on his defensive chops at second - he may be forced to re-convert to the outfield.

Mauricio Dubon - Boston Red Sox

Dubon began the 2016 season at High-A where he stole 24 bases in 278 plate appearances with more walks than strikeouts. He was properly challenged with a promotion to Double-A. The stolen base rate cratered to just four in 209 plate appearances. He now strikes out about four times more often than he walks (4.8 percent walk rate, 15.8 percent strikeout rate). However, his power numbers have taken an uptick.

A 22-year-old shortstop prospect, Dubon has the necessary traits to be a future dynasty asset with 10 home run upside and 15 steal speed. A lack of standout tools may push him into a super utility role where he'll really need to shine to earn regular reps.

Adam Frazier - Pittsburgh Pirates

Sometimes dynasty assets are sitting right under our noses, buried on the depth chart. Frazier, a 24-year-old utility man, is batting .338/.365/.493 in 74 plate appearances. His numbers are buoyed by a .397 BABIP and a high-for-him .155 ISO. He typically ISOs below .100.

At the plate, Frazier strongly reminds me of DJ LeMahieu. He features high contact rates with a ton of line drives, ground balls, and hard contact. While practically 99 percent of hitters are either of the pull or through-the-middle variety, Frazier has an opposite field stroke. The bottom line - if he were ever given a chance, he could hit for a high average with 20 or more stolen bases.

A.J. Puk - Oakland Athletics

There are two types of leagues - those where Puk is owned and those that don't let you pick up the current class of draftees. If yours is one of the latter leagues, you may still have a chance to lay claim to an excellent dynasty asset. Puk is off to a strong start at Low-A with a 2.16 ERA, 11.52 K/9, and 2.16 BB/9. He's supposed to dominate at this level - it was a conservative assignment. He was working towards a five inning no hitter last Saturday before the Baltimore affiliate squeezed through a couple fifth-inning singles.

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