If you would have asked this Q a year ago I would have said the Mexicali has had a good record of safety and a high quality of life ranked among the top places to live in Mx. One cartel has controlled the city for a long time, without much violence. But it is a border city in a border state so anything can happen at any time. I really do not recommend unecessary travel along the frontera.
In jan there was the killings at la resaca bar now attributed to sinaloa.
The massacre in La Resaca is considered different to the many others that happen in Mexico. The people who died that day were considered the leaders of the Beltran Leyva cartel in Mexicali; they were killed by people from the Sinaloa Cartel. Control of Mexicali passed from one cartel to the other.
the Mexican Army knocked off the two month leadership in april as the army captured Jesus Raul Ochoa Zazueta, identified as the alleged leader of the Sinaloa cartel in Mexicali, Baja California.
The flip side is that violence could be generated as the two cartels fight for the leadership again.
I do not recommend travel to any border state. There are many safe states in Mx to visit but this s not the time to visit Mexicali.