Hamels has a case, he's up to 58 bWAR, pretty close to the threshold for HOF (which in my mind is around 60?). Cole and Nola have a chance based on their age. Sale was for sure on the right trajectory before he got hurt.
https://www.baseball-reference.com/leaders/WAR_pitch_active.shtml
Changing it to career WAR leaders, only four pitchers have gotten 63 WAR and aren't in the Hall of Fame.
Schilling is left out because he's an a-hole, but still has a chance.
I don't know anything about McCormick, Tiant or Brown.
Under 63 WAR, not being in seems commonplace, but there are a lot until about 50 WAR.
Almost all Hall of Fame pitchers so far are starters, but there's probably a separate WAR requirement for relievers going forward.
There are a bunch of active starters with enough WAR, but many of them will be short in traditional categories like wins that used to determine successful candidates.
https://www.baseball-reference.com/leaders/WAR_pitch_career.shtml
EDIT: McCormick was born before the civil war, so everyone probably discounts his 76 WAR.
Tiant not getting in is a bit of a travesty.
Kevin Brown owes all of his WAR to consistently being good, but never great. He probably should get in, but plenty of "very good" hitters aren't of the HoF...
Also note, I missed a guy named Clemons at first, because he's so close to to the top of the list.
Never heard of him.