Earlier quoted context omitted.
I had a recent 30 day delinquent payment reduce my credit score by 80 points. And this was because the letter in the mail was mid-delivered. Not that the credit card issuer, nor the credit agencies give two shits. This was after about 5 hours of calls ping-ponging between the two.
Credit scores change constantly. What your 80 point drop told creditors is "This person might not have enough money to pay their bills, or is careless or forgetful.". You are perceived as higher risk because, statistically, you are a higher risk. Those of us who maintain excellent credit do it in part by making sure our money gets where it's supposed to. I check online to make sure payments post, or hand in payments…
Is an oxymoron. Statistics exist when "you" is unknown.