do you believe in clutch hitting and momentum?

I believe in momentum as a psychological thing. I think the math geeks have pretty much proved clutch hitting doesn't exist.

I agree with you but I also think momentum can carry over from game to game, whether individually or for an entire game. Hit streaks and win streaks are more than math, they're guys settling into a groove. Sometimes a player is just seeing the ball really well or comfortable with his swing. Sometimes a team just gets everything going at once, and that collective focus provides momentum going from one game to the next.  It makes all the difference in the world when you get yourself into a particular mindset in sports.   

From a team perspective, look at the 2004 Red Sox.  If ever there was an example of momentum in the post season, it's them.  They were pushed to the breaking point after game 3 of the ALCS, played with 'house money' in games 4-5 and never really looked back, back door sweeping the Yanks and sweeping the Cards in the World Series.  Another classic example of momentum would be the 2007 Rockies.  They won a million games in a row to end the season and swept their way to the World Series...then they had to wait for the winner of a 7 game grinder of an ALCS, and then they were swept themselves by the Red Sox.  You have to believe that series would have been much more competitive if the Rockies had the chance to continue rolling instead of sitting around waiting for the World Series.       

No, and I believe that the vast majority of stats in sports period are nonsense.

One of the problems in baseball in my opinion--and don't get me wrong, I'm a baseball fan--is that things are too balanced. I really don't believe that the outcome of baseball games, seasons, etc. is much different than chance would have it.

I'm not saying that no trends show up when we analyse the numbers of what happened, by the way. I'm saying that I don't at all believe that those numbers have anything at all to do with what's going to happen now or in the future.  The stats have zero causal implications in other words.  From a current, causal perspective, baseball might as well be completely random.

In sports in general, I do believe that there can be more or less talented groups of players, and in sports where the balance of that is really off--basketball for example, that's just as much of a problem.

I also think that a team's "culture" has a big impact--how the guys on the team tend to interact with each other, and how management, ownership etc. tends to interact with the team. That's a far more relevant factor than any stats.

I think the sports focus on stats is just an example of narrative-building, a fictionalization (the idea that they're relevant to anything that's going to happen now or in the future) that makes the game more interesting and that appeals to more numbers and minutiae-oriented fans. It also appeals to the same traits that fuel superstitions, and sports are rife with superstitions.

Put it here brother

Momentum absolutely exists, especially in baseball where hot hitting from guys in a lineup has an amplifying effect on other hitters in the same lineup.

I mean, how could anyone say otherwise when pitchers literally change their entire approach, change the pitches they'll throw, nibble the edges of the strike zone, and become far less aggressive when guys are on base and/or they're worried about the next hitter in the lineup?

Also, stats show that some hitters absolutely do get more hits and drive in more runs with RISP. There are also stats showing some hitters feast on the back ends of rotations, which is why you see some guys who have gaudy offensive numbers in the minors but still aren't considered MLB material -- those dudes are cleaning up on bad pitching, but aren't effective against major league level pitching.

Nobody said it was magic. The team's mentality changed once all the expectations went out the window. They played fearless baseball and started hitting on all cylinders.  Suddenly the pressure (and are you going to argue pressure isn't real in sports?) was all on the Yankees again.   

This reminds me of analytics people saying there is no such thing as 'being in the zone.' There absolutely is such a thing.  Sometimes you're having a good day, sometimes you're in the zone.  You can feel it.  It's beyond confidence, it's muscle memory taking over.  You remove all doubt of the outcome (and honestly any thoughts of anything at all) and simply do it.  If you've taken part in any athletic endeavor and never been in the zone, I pity you.   

Momentum and clutch play are real elements that simply cannot be measured, because they represent the psychological aspect of sports.  Look at Super Bowl LI.  Was there no momentum shift in that game?  The Patriots scored 31 unanswered points!  "We'll they just as easily could have scored 31 unanswered points to start the game."  But they didn't.  They did it after trailing 28-3.  That's called momentum. 

Momentum is, if nothing else, an increase of focus which brings an increase to efficiency.  Momentum is the opposite of frantic.  Blowouts happen is sports (particularly in football) when a team gets down and tries t make big plays out of nothing instead of staying the course.  This desperation leads to mistakes, and the blowout gets worse.  They never gain momentum because they are playing frantically.  Nobody panicked on the Patriots.  They steadied the course and played virtually error free football down the stretch.  That focus gave them momentum, and that momentum carried the day.  Meanwhile the Falcons panicked, made poor decisions and ceded the momentum they previously had to the Patriots.  It can't be math or 'The Patriots were the better team coming into the game' once they were down 25 points.  There's a mental aspect to all of this that you're completely disregarding. 

So if momentum is the opposite of frantic play, then 'clutch' is the opposite of panicking.  It isn't magic and it isn't math when the same great players win again and again and again.  It's mental preparation, plain and simple.  Watch the mic'd up NFL film of the Super Bowl.  The Falcons are up 21-0 and two Atlanta players are openly discussing Tom Brady's ability to bring his team back (and of course it isn't him alone but that's not the point here).  Meanwhile the Patriots at one point are down 25 points and Julian Edelman says to Brady, "It's going to be a hell of a story," to which Brady simply replies, "Yup."  Now tell me who was mentally prepared to make 'clutch' plays in this game?  The team up three TDs and worrying about what's going to happen down the stretch, or the team down 25 points who still fully expect to win the game?  

That mental preparation is what leads to 'momentum,' moment to moment, game to game, season to season.  But it's absolutely real.  The trick isn't 'believing' in momentum or 'clutch play,' it's understanding that these aren't abstract 'magical' concepts.  They are mental aspects of the game that do not show up in a stat sheet but are totally under your control.