The young right-hander failed for the first time, though how it changed his value moving forward remains to be seen.
Giolito, now just 22 years old, posted a 6.75 ERA in six appearances with the Nationals.
The Nationals now have a full bench, as Taylor returns after more than a month in the minors.
The Nationals' top prospect's velocity sat between 93 and 94 miles per hour Sunday.
The Nationals have pushed back their four main starters to eliminate the need for a fifth.
News and notes from this week in the Nationals minor league system.
A busy afternoon for the Nationals left them with a stronger bench and an extra man in the bullpen.
The rookie's second start did not last as long as his first, though it revealed more about where he is now.
Things to think about heading into an important four-game set at Citi Field.
Ross was put on the 15-day DL with right shoulder inflammation.