Pena is a 21 year old in low-A throwing 94-95 with a good breaking ball and a 4.17 ERA, he would rank behind most of the relievers they just took.
Beyond the 5th round pitches, Christian McGowan (7), George Klassen (6), Andrew Baker (11) was overslot but only to $200,000, I think there are Matt Osterberg (14) believers, I am not one but he is pitching decent in AA, Drew Garrett (19) missed a bunch of time but the stuff is looking better, Casey Steward (19) is a legitimate prospect as is Jake Eddington (7). Beyond draft, Tommy McCollum, Andrew Walling, Tristan Garnett, and to much lesser extents Danny Wilkinson and Braeden Faunaught all have performed well as UDFAs.
Hitters T.J. Rumfield (traded for Nick Nelson, Donny Sands) is a decent-ish prospect in the Yankees org. Barber flat out said yesterday to the beats he doesn't think there are good hitters late. Rincon is still stock up, he is just currently hurt, but he is a universal top 15 prospect in the org. Caleb Ricketts (7) is stock up for a 7th round pick. Otto Kemp (UDFA) is about to be on lists.
I don't really trust them with improving hitters, it is why I am not bullish on this draft because I think there is work to be done at the top and I don't trust it. That said, they have consistently turned stuff based pitchers into better pitchers. I realize Griff McGarry is a name that people go "bust" to, but he was an underslot 5th round pick. Alex McFarlane looked on a breakout path last year before the elbow went. It is all small sample size, but also look at what the Dodgers and Rays do, they take college arms with interesting traits and then they improve those guys. If my count is correct there were 26 HS SPs taken total in the first 11 rounds, 4 of them by the Brewers who likely went way underslot at pick 17 and 4 of them by the Guardians who had the largest bonus pool this year.