Don't twist my words.
Teaching English or doing any other illegal work is subject to disciplinary action on the part of Chinese Immigration authorities. Because media uses the word "deportation" to cover all instances of being booted out whether it was an official deportation or not, we don't really know the details. The Shanghai Daily isn't exactly a bastion of precision. My guess is that if this was a first offence by new foreign teachers (we're not too far into the academic year yet), they were simply booted out with a fine and a You're Blackballed from Working in China and a Don't Come Back for Awhile Even as a Tourist. If they have been in China awhile and were discovered to have been teaching illegally for one or more years previously, dodging and weaving to stay under radar, then chances of formal deportation go up. To some extent, punishment also depends on the clout (guanxi) of the employer and who needs protection vs scapegoating.