That 2012 Red Sox team was sitting at .500 at the All-Star break and didn't turn into your "69-93" team until literally August/September when injuries decimated them. In fact, going into August they sat at 53-51, which means that for 4 of the 6 months of that season they were actually a fairly average team. How does it relate with our Blue Jays team this season? Well, if you have been paying any attention, you'd understand that this team has spent a grand total of 0 days at .500 or better this season, and that apart from one stretch wherein we beat up on an equally injured Seattle team and Cincinnati, we have been a BAD team for virtually the entire season. So to begin, we need to clarify that you are actually comparing what was an average-ish 2012 Red Sox team who just so happened to have a horrible end to their season to a bad 2017 Blue Jays team that has been bad for the majority of games played to date. As you can hopefully imagine, it is a lot easier to take an average team and improve them enough in one offseason to get a good team the following season than it is to do the same with what is a bad team the year prior. So in reality, the starting points aren't even remotely comparable.
You then need to analyze their free agent signings from that offseason and understand that expecting that type of reproduction or luck is beyond silly. Yes, baseball is random, but if you operate your franchise under the premise that you will replicate that 2013 Red Sox free agent class you are going to have a bad time. They got 5.9 WAR from Shane Victorino who hasn't done a thing since that 2013 season. They signed Koji Uehara for $4.5 mill and he proceeded to produce a 3 WAR season in relief, at the time one of the most dominant single season relief performances in history. They signed Napoli for $5 mill and he produced a 3.9 WAR season. They signed Stephen Drew for $9.5 mill and he produced a 3.4 WAR season. Throw in Saltalamacchia having a fluke 3.5 WAR season himself and it is easy to see how they fluked their way from average to very good in one offseason. Sounds simple, right? You just need all your pedestrian free agent signings to put up elite seasons at the same time. Not just good, but elite. This was of course a complete fluke as most of those same players went on to fall back to reality in 2014 which led to a 71-91 season.