Always the “two” of the Bulls’ one-two punch, Scottie Pippen’s legacy as a lifetime second best player is inarguable (minus a couple seasons when MJ took up baseball). Who’s the equivalent in MLB?

People always use the “how can he be in the Hall if he was never the best player on his team?” argument, and it’s kind of annoying for two reasons: it’s false, and the player likely was the best player on his team at least once.
So I posed a question on Twitter, asking the masses who they thought the best player in MLB history was, who never was the best player on their respective team(s). A lot of people were objectively wrong, sorry. For example, while Derek Jeter may have been overrated, he was the best player on his team at least twice. While Babe Ruth was Lou Gehrig’s teammate for a good portion of Gehrig’s career, Gehrig was the best player in the league during and after Ruth’s decline.
I didn’t get any “wow” comments, that were clear cut answers, so I decided to take matters into my own hands, using numbers. While WAR is nothing more than an approximation or a guideline, I figured it’d be the easiest first step to take. I put a few qualifiers, but don’t remember all of them. I believe it was 5000 PA or 2500 IP in the 20th / 21st Centuries, which left something like 300 players left. Anyone who didn’t make that cut probably would not be the answer to my original question as they didn’t have the longevity.
Of those players, I used Excel to find which of them never led their team in fWAR (or tied with someone else). I collected a reasonable number of players, some of whom sucked, so I set the minimum at an arbitrary 50 career WAR. This left me with 15 players who had good careers but never led their team in WAR. They were, in order of career fWAR:
Eddie Plank, Tom Glavine, Juan Marichal, Early Wynn, David Wells, Bill Dickey, Luis Gonzalez, Curt Simmons, Gabby Hartnett, Willie Davis, Jerry Reuss, Bartolo Colon, Tommy Leach, Mickey Cochrane, Tony Lazzeri
Of them, eight are Hall of Famers, and one is active. Let’s limit this down further.
First, I’ll remove all players who won an MVP. While advanced stats are telling, if a player won MVP, he was seen by many as the best player in the league at least once, meaning he was the best player on his team. This takes Gabby Hartnett and Mickey Cochrane out of consideration.
Now, I’ll take out the seven players with the lowest career WAR/season (of the thirteen remaining). This eliminates Luis Gonzalez, David Wells, Curt Simmons, Tommy Leach, Bartolo Colon, Early Wynn, and Jerry Reuss out of consideration, leaving only Plank, Marichal, Lazzeri, Dickey, Glavine, and Davis. I’ll eliminate Davis as he is not in the Hall of Fame like the other five.
Of the five that are still there, who was the best player? Using Jay Jaffe’s WAR7 concept, which looks at a player’s total WAR in their seven best seasons (not necessarily in order), we can find who had the best peak, and effectively were better ballplayers. The top two remaining, after eliminating the worst three, are Juan Marichal and Eddie Plank. Yes, I know WAR7 uses bWAR not fWAR. Whatever.
Let’s compare the two finalists, since they were both pitchers:
Marichal: 123 ERA+, 61.9 bWAR, 61.2 fWAR, 243–142, 2.89 ERA, 3.04 FIP, 16 yrs
Plank: 122 ERA+, 86.5 bWAR, 67.8 fWAR, 326–194, 2.35 ERA, 2.45 FIP, 17 yrs
It’s pretty close, but I’ll give my Scottie Pippen Award to Eddie Plank.
To answer my own question, Eddie Plank was the best player in MLB history who was never the best player on his team. He was overshadowed by guys like Rube Waddell, Eddie Collins, Home Run Baker, and Chief Bender.