San Francisco Giants: Will these relievers be part of the 2020 bullpen?

RHP Jandel Gustave
Sense a pattern here?
Flame-thrower Jandel Gustave gives the San Francisco Giants another potential late-inning option thanks to his high-octane stuff.
The 26-year-old has an average fastball velocity of 96.2 mph, which is quite a bit higher than the league average of 93.4 mph.
In 20 appearances this season, he has a 1.61 ERA and 0.80 WHIP in 22.1 innings of work, though he has managed just 10 strikeouts against six walks.
Opponents are hitting a meager .182 against him this season. He has limited left-handed batters to a .233 average and a 2.13 ERA, while right-handed hitters have batted just .149 with a 1.80 ERA. His WHIP against right-handed batters is an astounding 0.67, as opposed to a 1.36 WHIP against left-handed batters. Either way, all these numbers are very promising.
Still, there are a few reasons to hold back from giving Gustave a late-inning role at the start of next season.
The first would be that this is only his third year at the MLB level, which means he could be lacking the experience needed to lock down a game. There’s also the fact that his numbers with the Houston Astros weren’t great before he made his way to San Francisco. He had a 3.52 ERA in 2016 and a 5.40 ERA in 2017, so there’s not exactly a lengthy track record of success.
At the very least, Gustave deserves a longer look when spring training starts next February.