If you scroll down further in the article, you'll see that those are cropped images of the cores. The cropping is off-center, not the cores. Otherwise, they would wobble terribly when thrown or hit.
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.
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!
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.
I also agree about protection, being hit by a cricket ball is something you don't forget, and can indeed be lethal[0]
0: minus the occasional Chris Gayle blast out of reach of anyone, I imagine
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.