Mariners are about to welcome back final puzzle piece for their pennant chase

It's rare for teams to add impactful players after the trade deadline. Usually, the only external players that are available are those who have been released, designated for assignment, or were free agents that never found a home to begin with. Internally, rosters for playoff hopefuls get upgraded in two ways: late call-ups and returns from the injured list.

For the Seattle Mariners, the latter could hold the secret to getting another leg up over the competition.

There are several key players who have officially started rehab assignments and they've all been going well. Luke Raley has posted a 128 wRC+ in his second rehab stint of the year with the Rainiers and has undoubtedly re-entered the postseason roster conversation. Other than some hazardous conditions, Victor Robles has looked good in the few Triple-A games that he has played so far. However, the player making the most anticipated return is the one with the greatest chance of making a playoff splash.

Bryce Miller looked outstanding in his final rehab start and looks ready to return to the big leagues

In what may be his final outing in the minor leagues, Bryce Miller looked like his old self, cruising through four perfect innings and sitting in the upper-90s on his fastball. His final line was 5.2 innings pitched with two hits, two earned runs, one walk, and four strikeouts.

He also topped out at 98.1 mph, which is nearly 1 mph faster than the fastest pitch he has thrown in the big leagues all season, so velocity clearly isn't an issue for him. Still, he seems susceptible to barrels, as he gave up at least one home run in each of his last two rehab outings. Nonetheless, with his arm and elbow looking great, the swing and misses likely aren't too far behind.

The timing of his recovery couldn't be better. Despite getting off to a great start, Logan Evans has posted a 5.63 ERA over his last five outings and doesn't seem fit to hold down the back of the rotation in a crucial postseason series. Miller will bring along questions of his own, but with more of a proven track record in the majors and a clean bill of health, he brings along far more upside than Evans.

The Mariners are now in a sprint to the finish line. Although their postseason spot is all but secured, the most recent series against the Baltimore Orioles should demonstrate that they're not immune to failure, even at the hands of a team that's 11 games below .500.

Now that the Houston Astros are back to a 1.5-game lead over the Mariners, Seattle must utilize every advantage they can get in the final few weeks. Bryce Miller's return could transform the team from scrappy underdog to World Series contender.