Pennock is not unworthy of the HOF; he's really not as bad as a lot of people say. He's not a top rank pick, however. The guys on Double X's list were all better.
Pennock's death was sudden. He was an educated man, and well thought of. He served as GM of the Philadelphia Phillies from 1943 until his death, so he was active in baseball at the time of his death. That's the kind of thing that can give you uumph with the writers. His work was helping the Phillies improve; he laid the foundation for what became the Whiz Kids of 1950.
Had Pennock not gone in at the time he did, he may never have gone into the HOF. He certainly would never be inducted now. The reason is not his stats; it's his legacy of racism. Pennock was opposed to the integration of baseball, and told Branch Rickey so:
Not all of the Phillie racism of the day was Pennock's fault. Some of it started at the top with Owner Bob Carpenter. Then, too, there was Ben Chapman, the Phillie manager in 1947 and a viscious bench jockey who rode Jackie Robinson more mercilessly than any other. But Pennock was a big part of the Phillie racism. People overlooked that in 1947; even condoned that, but if he were on the ballot of the VC today, his racism would be the story in every article about his HOF prospects, I guarantee it.
"[You] just can't bring the n----- here with the rest of your team, Branch. We're just not ready for that sort of thing yet. We won't be able to take the field against your Brooklyn team if that boy Robinson is in uniform."
"I do not care if half the league strikes. Those who do it will encounter quick retribution. All will be suspended and I don't care if it wrecks the National League for five years. This is the United States of America and one citizen has as much right to play as another. The National League will go down the line with Robinson whatever the consequences. You will find if you go through with your intention that you have been guilty of complete madness."
NL President Ford Frick, 1947