Remember, new ratings talk around here. Instead of providing just the numbers, I'm putting them into context. If you see something like "110 A18-49", that means a show on average rates at 110% of the network's A18-49 demo average.
The Ratings
Son of Zorn gets the fortune of airing Sundays at 8:30 on FOX, which is the best time slot a comedy on the network can ask for. On average, it gets a 114 A18-49 out of a 165 from The Simpsons, and a 146 M18-34 out of 217 The Simpsons. While not terrible retention, it perhaps could be doing a bit better. Also, its ratings on non-football-boosted nights are around the same as live action shows like New Girl and Brooklyn Nine-Nine, despite them having lower-rated lead-ins. It's constantly getting boosted by football-boosted The Simpsons, but the problem is it isn't holding a lot of that lead-in.The Advantages
One of Son of Zorn's biggest advantages is the names behind it; specifically, Lord Miller Productions. FOX seems to like being in business with the production company that also backs The Last Man On Earth, the upcoming Making History, and a new pilot for ABC (distributed by 20th Century Fox). A relationship with them, combined with the fact that the ratings aren't that bad, could lead to a renewal.
Another factor is that it's an on-brand comedy that seemingly is designed to only do short seasons. By ordering a short season 2 of Son of Zorn, FOX can focus more promotion on new shows instead of getting too ambitious and premiering too many of their new shows at once.
The Disadvantages
Son of Zorn is one of FOX's highest-rated shows due to its time slot. However, it looks somewhat weak compared to its lead-out, Family Guy, which on average grows from it in both 18-49 and 18-34, both genders included. Given that Family Guy doesn't enjoy as much of a football-related boost as Son of Zorn does, this could be pretty troublesome for Son of Zorn. Additionally, the premiere of The Mick put it to shame, getting a higher rating out of a much lower lead-in. Time will tell if that holds, but it's definitely not a great sign for Zorn.
Outlook
The second factor I listed under the advantages column pretty much sums up my feelings of Son of Zorn's chances of returning. It's not exactly a strong show, but it's not the biggest of flops either. Sticking it at 9:30 pm on Sundays next fall would be a way to put promotional focus on something at 8:30 and shows across the rest of the week.