The intention of the Rule is to prevent a player from using balls with different playing characteristics depending on the nature of the hole or shot to be played during a round. The Rule is intended to be used only in very high-level events, not by weekend golfers like most of us. Well, let’s see what the Rule actually says, in this case Model Local Rule G-4:
During an entire round, each ball at which the player makes a stroke must be the same brand and model as found in a single entry on the current List of Conforming Balls.
If a different brand and/or model is dropped, replaced or placed but has not yet been played, the player may correct the mistake by stopping use of that ball, without penalty, under Rule 14.5. The player must drop, replace or place a ball of the same brand and model as used at the start of the round.
When the player discovers he or she has played a ball in breach of this Local Rule, he or she must stop using that ball before playing from the next teeing area and complete the round with a ball of the same brand and model as used at the start of the round; otherwise the player is disqualified.
If the discovery is made during the play of a hole, the player may complete play of this hole with the ball played in breach or place a ball of the correct brand and model on the spot where the ball played in breach of this Local Rule was lifted from.
Penalty for Making a Stroke at a Ball in Breach of Local Rule:
The player gets the general penalty for each hole during which he or she is in breach of this Local Rule.
So one important part, in the first paragraph, a single entry on the list of conforming balls. If you actually go and look at the list, the year isn’t mentioned, but very specific descriptions of the markings ARE listed. If the 2020 and 2021 balls are labelled differently by the manufacturer, the player broke the rule. Heck, the description of the Rule specifically says that balls of different colors (i.e. white and yellow) are considered different balls under this rule.
The other important part, as I read the Rule, the player can correct his mistake before he tees off on the next hole. In this case, the player knew he had changed balls, teed off on the next hole, and so was DQ.
Is the reason for the rule a valid one? I’d say yes, otherwise a player may hit a higher-launching ball on some holes, a lower-spin ball into the wind, etc. How do we define “same ball”? It seems logical to use a single entry on the conforming ball list, seeing as how Titleist has 3 full pages of balls listed.
Knowing all this, why did the player have balls with different manufacturer’s markings in his bag? I can understand him not knowing all the details of every Rule, but one common thread throughout the rules is that you can “fix” many mistakes with limited consequences if you do it as soon as you realize your error. Beginning a new hole without correcting the problem is almost always a bad choice. If he knew that general principal, he might have asked the appropriate question of the Rules Official he talked to, or he may have remained patient enough to get the Ruling before playing onward.
So I’d say the Rule itself is NOT asinine, it has e legitimate reason, and is written in a way that makes it enforceable. I’d say the player didn’t know the Rule well enough, but its a really small detail. The player (and caddie?) could have prepared better, by making sure every ball in his bag was marked the same. I’d say the Rule Official could have done a better job, specifically by telling the player not to start a new hole with the “wrong ball”. The player, likewise, could have known the rules well enough to realize that starting a new hole could aggravate a problem. To me, fingers can, and should, be pointed in a bunch of directions.