The two balls in the first column (so one old and one new) have a pretty symmetric distribution, but look closely at the others. Some are ridiculously uneven.
Yeah, but that doesn't matter here because it's present in both the newer era balls and the older era balls. We also know that seven of these are used baseballs, meaning they could very well be deformed or off center from use. There's a reason that they only use a baseball for about 8 pitches. (https://www.foxsports.com/other/story/major-league-baseballs...)
In cricket the same ball is used for 480 balls (depending of format). Initially the new hard ball is seen as an advantage to the fielding side as a bowler gets more bounce and deviation from the hard seam, but a batsman can also hit it further. There is also the phenomenon of swing (a bit like the curve ball in baseball) which is accentuated by the fielders polishing one side of the ball. As the ball ages and softens it's bounce becomes more true and therefore it favours the batting side. Often towards the end of its life the ball develops 'reverse-swing' where it curves the opposite way. They have to keep the 'rough side' of the ball completely dry to do this, so all fielders have to keep their hands dry. Penalties have been applied to players trying to alter the condition of the ball. Different brands of ball are polished differently and swing at different times. Some even have a lacquer which takes a while to come off and start swinging at all
why I think this is relevant
1) The aerodynamic effects of the kind polish applied dramatically affect performance
2) Since wear on the ball is critical to the long format games, the fans don't get to take one home and sell it on ebay, even if they catch a six (ball hit into the crowd) :(
The significant change in cricket hitting has been massively heavier bats, which used to be made of compressed willow to preserve their life (a whole season for a pro), but are now made of unpressed willow and considered disposable. The unpressed bats work much like corked baseball bats are supposed to, and have transformed the game. Slow-bowlers, like spin bowling where the bowler spins the ball to alter its flight and make it move when bouncing, have to be exceptional now or they get smashed into the car park!
The most significant change in cricket has been covered wickets when it rains. If you have ever had the fun of playing on an uncovered wet wicket you will understand how elite teams were able to be bowled out for under 20 runs on wet wickets.
I also think more body protection has played a massive role in more aggressive batting. When I was young I used to play with nothing more than pads, gloves and a box and had to face bowlers who could bowl over 140km/hr on very unpredictable wickets. I got out more than once getting out of the way of some bouncer that stayed low as I was looking to avoid getting hit. I have been hit enough times with a cricket ball to have learned self-preservation is the better part of valour.
As a teenager growing up in the UK I played cricket for my school and a local team, and when I was about 14 I had the "pleasure" of facing roughly four balls bowled by the Legendary West Indies cricketer Viv Richards[1] when he visited my school. I somehow managed to get the bat onto the first ball and score a 4, at which I foolishly celebrated shouting something along the lines of "in your face, I thought you were a professional cricketer!" What a stupid, stupid thing to do.
There then followed a three ball lesson in bodyline bowling until I literally lost my bottle and refused to carry on leaving the wicket with what little dignity I had left. Seriously, seeing that giant six-foot tall man taking a run-up and then bowling a cricket ball at my head at what seemed like supersonic speed literally scared the crap out of me.
You are right about the covered wickets, although when I started watching cricket in the 1990's they were already universal in the elite game. I should correct my statement and say that heavy bats have been the most significant thing in the last 20 years of the elite game with regards to big hitting.
I also agree about protection, being hit by a cricket ball is something you don't forget, and can indeed be lethal[0]
It is possible that a ball can be hit out of a stadium and not be returned (but it is usually very rare due to stadium sizes and layouts).
If that happens they have a tray of prepared balls of different states, then they'll select one that most closely matched the previous one's condition/age etc.
The background images appear to actually be a video or something, but here's a screenshot I took:
https://share.neosmart.net/View/Index/nfgSDo.png
The two balls in the first column (so one old and one new) have a pretty symmetric distribution, but look closely at the others. Some are ridiculously uneven.