WASHINGTON -- The Marlins utilized the onset of the new month and its expanding rosters as a September activation period rather than one of callups. Miguel Rojas and Tayron Guerrero were both activated off the 10-day injured list, while José Ureña made his return from the 60-day IL ahead of Sunday's 9-3 loss to the Nationals at Nationals Park.

Rojas went 0-for-4 with a fielding error, while Guerrero was tagged for a two-run homer in the seventh.

Urena, who will serve as closer when a save opportunity arises, needed just 11 pitches in a scoreless eighth. His two-seam fastball maxed out at 98.3 mph -- the fastest he has thrown a pitch since last season.

"We really figured that Jose would tick up out of the 'pen and that he would come in and let it go," Marlins manager Don Mattingly said. "I’m interested if we can get a lead and hold it, let’s see what he looks like out there."

So while the Marlins do plan on making a few more additions to their roster over the course of the month, none will come until the team heads to Pittsburgh, at the earliest, and indications are that none will come in the form of their top prospects.

Part of that can be attributed to the fact that a couple of the higher-touted prospects have already been with the team for some time now. Such is the case with Isan Diaz. But there is no expectation that top prospect Sixto Sanchez and Jorge Guzman (No. 17 prospect) are in line to join the team from Double-A Jacksonville.

Along with a likely catcher, a couple of arms that could be called up to join a beleaguered bullpen include 30-year-old lefties Brian Moran and Mike Kickham -- both with Triple-A New Orleans. While the latter would appear in the Majors for the first time since 2014, the former would make his big league debut if he earns the call.

If he is indeed given the nod, Moran would bring with him an impressive 76 strikeouts compared to 26 walks in 59 innings at the Triple-A level this year. Lefties are hitting just .089 off him.

“It gives us a chance to have extra arms so you’re not taxing the bullpen as much,” Mattingly said of the benefits of September, which comes after the team's 7-22 month of August. “You can give guys rest on the offensive side, too. So hopefully, that’s going to be something that helps us.”

Without much in the way of new prospect excitement heading into the final month of the season, here’s a look at a few guys who are worth keeping an eye on with competitive baseball in the home stretch:

Arrival: Infielder Isan Diaz
Level: Major Leagues
Prospect ranking: No. 5 (MLB No. 82)
Of note: .157/.268/.253 slash line in 24 games

It would be hard to make a bigger immediate impression than Diaz, who homered in the third at-bat of his career -- off Jacob deGrom, no less -- in front of a score of friends and family for a now-viral moment that captured the hearts of many. But the big league level has not been nearly as kind to Diaz since then.

The 23-year-old second baseman, acquired in the Christian Yelich trade, has been kept out of the lineup two consecutive games in D.C. after going 0-for-4 on Friday, albeit drawing a bases-loaded walk in the process.

Breakout: Right-hander Edward Cabrera
Level: Double-A Jacksonville
Prospect ranking: No. 7 (MLB No. 100)
Of note: Opponent average of .190 across 19 starts in 2019

Cabrera always had top-of-the-rotation potential. The 21-year-old put it all together this year, starting off at Class A Advanced Jupiter and finishing up at Double-A. He just entered MLB Pipeline's Top 100 rankings. Cabrera, who throws in the upper 90s, has improved his secondary pitches and command. He combined for a 9-4 record and a 2.23 ERA, with 116 strikeouts in 96 2/3 innings.

Something to prove: Outfielder Connor Scott
Level: Class A Advanced Jupiter
Prospect ranking: No. 15
Of note: 28 doubles and 23 stolen bases across 122 games in 2019

Scott, Miami's first-round Draft pick in 2018, dropped out of the organization's Top 10. The left-handed-hitting outfielder shows plenty of potential defensively and is a plus runner. The question is if he will consistently hit. Scott spent most of the season at Class A Clinton, batting .251/.311/.368 in 95 games. He was promoted to Jupiter, where he hit .235/.306/.327 in 27 games.

Name to watch: Left-hander Trevor Rogers
Level: Double-A Jacksonville
Prospect ranking: No. 9
Of note: 4.55 strikeouts-to-walks ratio across 23 starts in 2019

Rogers, the 13th overall Draft pick in 2017, was arguably the organization's most consistent pitching prospect from start to finish. The 6-foot-6 left-hander made a case to be its Minor League Pitcher of the Year, posting a 2.53 ERA in 18 starts at Class A Advanced Jupiter. He finished up with five starts at Double-A, going 1-2 with a 4.50 ERA in 26 innings, with 28 strikeouts and nine walks.