Okay, I'm not gonna claim to be an expert but have you tried to play tennis then suddenly add 5g randomly to your racquet? Do you play tennis competitively? Are you able to play at that high level and go for your shots in high pressure moments with confidence again and again?
I certainly don't but I will say 5g is a massive amount to add for a pro relatively shortly before a Grand Slam. 10g is generally considered to be a different racquet all together. They make different models of similar racquets with only 10g difference. His team put it near the middle but it still might affect your confidence in moments and tennis can be a game of centimetres. Playing against an ATG putting your game under stress will not help
Try 3g or even 1g at the tip next time, you will know. I just wanted to say that today
I still think he was going to lose to Djokovic today, the way Djokovic adapted his game to his injury, however serious it really is, was impressive. Alcaraz did not have to ground game or tactics to win today. The little change to serve style also might not have helped. He likely needs a better coach and racquet setup. He's been able to get away with close to stock specs for much of his career due to his physicality and talent but some people it seems can see he needs to try too hard for too long to create that heaviness of shot, unlike Novak. Or what Wawrinka was able to do at times to Novak, I've yet to see Carlos do that consistently with his groundstrokes to Novak. You can see weight and quality of shot better in person and looking how it affects the opponent
The 5g near the middle was likely just for stability and power, maybe for returns or serve as we've been told. 5g total weight will still add power even if SW does not change as much