I would say Deacon McGuire, who played for the 1904 NY Highlanders in their final series against the Red Sox. That series was the last time until 1951 that a pennant-deciding series was clinched in NY, (more specifically at Coogan's Bluff, though a different ballpark) denying a NY team a trip to the WS. And McGuire had a part in the decisive play of 1904 as well, being unable to handle a wild throw to home that let Boston score the winning run. After they managed to hold down the almost-yankees in the bottom half of the inning, the almost-Red Sox clinched the pennant.
 

Dave Kingman was a member of the Mets, Padres, Angels, Yankees, and Cubs, all within a 6 month period in 1977. He was traded to the Padres for Bobby Valentine and Paul Siebert. Bobby Valentine is the son-in-law of Ralph Branca, who of course gave up the 'Shot Heard Round the World'.
 

Ryan--good effort. I guess you're talking about 1888 with McGuire playing for all those different teams. And nice connection, too. Not what I was thinking of, but I'll give you a half-point.

And the other 5.5 go to AJM, who nailed it! The comeback is complete! AJM was way down in this contest, and climbed all the way back to take second, edging out pweezil. So close, though. Pweezil, you'll get a book anyway..

But really nice job by AJM there, I didn't think he had it in him, but he scores a prize-qualifying spot for the third straight year, 1st/1st/2nd.

And this also means that Ryan is officially this year's champ. Congrats. Blog post to follow.
 

Finally, after that long stretch as the Obama-like near-certain winner, I can relax. Yes, I just compared your quizzes to the presidential race.

Incidently, McGuire seemed like a good candidate because he just barely had the "member of five teams" by playing for 3 in the 1888 season, then signing with another in the offseason, not playing with them, and signing somewhere else to manage the next year. Which is so obscure that it seemed like the type of thing you would use. Plus you wrote that cool post about 1904 recently.
 

Hearty congratulations to Ryan, who absolutely did an excellent job. The fact that I actually had my highest point total yet, and still finished several points out of first, really speaks to how dominant Ryan was this season. And congratulations and 'anti-terrible job' to Pweezil as well.

You're right, Jere, I didn't think I had any chance of placing in-the-money after my poor start this season. Looking forward to getting (and reading) your signed book..I hope your Mom is gonna sign it too!

The funny thing is, for some reason I was actually thinking about Kingman playing for four teams (all in different divisions)in '77 just the other day. I assume he must hold the record for most divisions played in during one season; of course back then four was the max, while today somebody could theoretically play in six. I'm convinced that the sole reason that the Yanks traded for him was to have him hit against the Sox in Fenway on 9/19 and 9/21...I still remember him hitting one of his typical sky-high homers over the Monster in that 1st game.

And I've met both Branca and Bobby V on separate occasions.
 

Congrats to Ryan and AJM.I'm way out of their league, both literally and figuratively, when it comes to baseball trivia. I've had the feeling for the last several weeks that AJM was an unstoppable train and was surely going to overtake me for second. He was and he did. Again, congrats to both of you.

Jere, the only thing more remarkable than your ability to come up questions that are extremely difficult to answer (for me, anyway) is your generosity! I really appreciate your sending me the book. I spend a lot of time reading and I'm sure I'm gonna love it.
 

Thanks for the kind words guys. If the contest had gone any longer either or both of you would have probably beaten me. I was a definitely lucky. And props to Jere for coming up with these ridiculously difficult and meticulously researched questions. It would be hard to overstate how cool it is that you give away prizes to people who already get a lot of enjoyment out of your writing to begin with. Well done all around!