About MLB’s New Mudding and Storage Protocol

My prior research on the slippery ball problem: Baseball’s Last Mile Problem

The TL;DR is that mudding adds moisture to the surface of the ball.  Under normal conditions (i.e. stored with free airflow where it was stored before mudding), that moisture evaporates off in a few hours and leaves a good ball.  If that evaporation is stopped, the ball goes to complete hell and becomes more slippery than a new ball.  This is not fixed by time in free airflow afterwards.

My hypothesis is that the balls were sometimes getting stored in environments with sufficiently restricted airflow (the nylon ball bag) too soon after mudding, and that stopped the evaporation.  This only became a problem this season with the change to mudding all balls on gameday and storing them in a zipped nylon bag before the game.

MLB released a new memo yesterday that attempts to standardize the mudding and storage procedure.  Of the five bullet points, one (AFAIK) is not a change.  Balls were already supposed to sit in the humidor for at least 14 days.  Attempting to standardize the application procedure and providing a poster with allowable darkness/lightness levels are obviously good things.  It may be relevant here if the only problem balls were the muddiest (aka wettest) which shouldn’t happen anymore, but from anecdotal reports, there were problem balls where players didn’t think the balls were even mudded at all, and unless they’re blind, that seems hard to reconcile with also being too dark/too heavily mudded.  So this may help some balls, but probably not all of them.

Gameday Mudding

The other points are more interesting.  Requiring all balls to be mudded within 3 hours of each other could be good or bad.  If it eliminates stragglers getting mudded late, this is good.  If it pushes all mudding closer to gametime, this is bad.  Either way, unless MLB knows something I don’t (which is certainly possible- they’re a business worth billions and I’m one guy doing science in my kitchen), the whole gameday mudding thing makes *absolutely no sense* to me at all in any way.

Pre-mudding, all balls everywhere** are all equilibrated in the humidor the same way.  Post-mudding, the surface is disrupted with transient excess moisture.  If you want the balls restandardized for the game, then YOU MAKE SURE YOU GIVE THE BALL SURFACE TIME AFTER MUDDING TO REEQUILIBRATE TO A STANDARD ENVIRONMENT BEFORE DOING ANYTHING ELSE WITH THE BALL. And that takes hours.

In a world without universal humidors, gameday mudding might make sense since later storage could be widely divergent.  Now, it’s exactly the same everywhere**.  Unless MLB has evidence that a mudded ball sitting overnight in the humidor goes to hell (and I tested and found no evidence for that at all, but obviously my testing at home isn’t world-class- also, if it’s a problem, it should have shown up frequently in humidor parks before this season), I have no idea why you would mud on gameday instead of the day before like it was done last season.  The evaporation time between mudding and going in  the nylon bag for the game might not be long enough if mudding is done on gameday, but mudding the day before means it definitely is.

Ball Bag Changes

Cleaning the ball bag seems like it can’t hurt anything, but I’m also not sure it helps anything. I’m guessing that ball bag hygiene over all levels of the sport and prior seasons of MLB was generally pretty bad, yet somehow it was never a problem.  They’ve seen the bottom of the bags though.  I haven’t. If there’s something going on there, I’d expect it to be a symptom of something else and not a primary problem.

Limiting to 96 balls per bag is also kind of strange.  If there is something real about the bottom of the bag effect, I’d expect it to be *the bottom of the bag effect*.  As long as the number of balls is sufficient to require a tall stack in the bag (and 96 still is), and since compression at these number ranges doesn’t seem relevant (prior research post), I don’t have a physical model of what could be going on that would make much difference for being ball 120 of 120 vs. ball 96 of 96.  Also, if the bottom of the bag effect really is a primary problem this year, why wasn’t it a problem in the past?  Unless they’re using entirely new types of bags this season, which I haven’t seen mentioned, we should have seen it before.  But I’m theorizing and they may have been testing, so treat that paragraph with an appropriate level of skepticism.

Also, since MLB uses more than 96 balls on average in a game, this means that balls will need to come from multiple batches.  This seemed like it had the potential to be significantly bad (late-inning balls being stored in a different bag for much longer), but according to an AP report on the memo

This seems generally like a step in the smart direction, like they’d identified being zipped up in the bag as a potential problem (or gotten the idea from reading my previous post from 30 days ago :)).  I don’t know if it’s a sufficient mitigation because I don’t know exactly how long it takes for the balls to go to hell (60 minutes in near airtight made them complete garbage, so damage certainly appears in less time, but I don’t know how fast and can’t quickly test that).  And again, repeating the mantra from before, time spent in the ball bag *is only an issue if the balls haven’t evaporated off after mudding*.  And that problem is slam-dunk guaranteed solvable by mudding the day before, and then this whole section would be irrelevant.

Box Storage

The final point, “all balls should be placed back in the Rawlings boxes with dividers, and the boxes should then be placed in the humidor. In the past, balls were allowed to go directly into the humidor.” could be either extremely important or absolutely nothing.  This doesn’t say whether the boxes should be open or closed (have the box top on) in the humidor.  I tweeted to the ESPN writer and didn’t get an answer.

The boxes can be seen in the two images in https://www.mlb.com/news/rockies-humidor-stories.  If they’re open (and not stacked or otherwise covered to restrict airflow), this is fine and at least as good as whatever was done before today.  If the boxes are closed, it could be a real problem.  Like the nylon ball bag, this is also a restricted-flow environment, and unlike the nylon ball bag, some balls will *definitely* get in the box before they’ve had time to evaporate off (since they go in shortly after mudding)

I have one Rawlings box without all the dividers.  The box isn’t airtight, but it’s hugely restricted airflow.  I put 3 moistened balls in the box along with a hygrometer and the RH increased 5% and the balls lost moisture about half as fast as they did in free air.  The box itself absorbed no relevant amount.  With 6 moistened balls in the box, the RH increased 7% (the maximum moistened balls in a confined space will do per prior research) and they lost moisture between 1/3 and 1/4 as fast as in free air.

Unlike the experiments in the previous post where the balls were literally sealed, there is still some moisture flux off the surface here.  I don’t know if it’s enough to stop the balls from going to hell.  It would take me weeks to get unmudded equilibrated balls to actually do mudding test runs in a closed box, and I only found out about this change yesterday with everybody else.  Even if the flux is still sufficient to avoid the balls going to hell directly, the evaporation time appears to be lengthened significantly, and that means that balls are more likely to make it into the closed nylon bag before they’ve evaporated off, which could also cause problems at that point (if there’s still enough time for problems there- see previous section).

The 3 and 6 ball experiments are one run each, in my ball box, which may have a better or worse seal than the average Rawlings box, and the dividers may matter (although they don’t seem to absorb very much moisture from the air, prior post), etc.  Error bars are fairly wide on the relative rates of evaporation, but hygrometer don’t lie.  There doesn’t seem to be any way a closed box isn’t measurably restricting airflow and increasing humidity inside unless the box design changed a lot in the last 3 years.  Maybe that humidity increase/restricted airflow isn’t enough to matter directly or indirectly, but it’s a complete negative freeroll.  Nothing good can come of it.  Bad things might.  If there are reports somewhere this week that tons of balls were garbage, closed-box storage after mudding is the likely culprit.  Or the instructions will actually be uncovered open box (and obeyed) and the last 5 paragraphs will be completely irrelevant.  That would be good.

Conclusion: A few of the changes are obviously common-sense good.  Gameday mudding continues to make no sense to me and looks like it’s just asking for trouble.  Box storage in the humidor after mudding, if the boxes are closed, may be introducing a new problem. It’s unclear to me if the new ball-bag procedures reduce time sufficiently to prevent restricted-airflow problems from arising there, although it’s at least clearly a considered attempt to mitigate a potential problem.