Hi zcdh30 -
Interesting question. I have a few thoughts to share from my 15 years as a Director of MBA Admissions at a top 20 school.
- Unless you worked for the professor, I'd be reluctant to use that person as an MBA recommender. My experience with professor-written recommendations is that they are focused entirely on classroom performance, and don't speak at all to professional performance or potential.
- A recommendation from a supervisor at a part-time job is fairly weak, unless you did something that made a significant impact to their business.
(So far, this is sounding pretty dismal, isn't it? Don't worry - I'll get to some positive news soon!)
- Your current supervisor may not be the strongest in terms of written language skills. However, if he can provide the Admissions Committee with insights into your professional performance, then it is of value. The committee will not judge *you* by his lack of grammar, etc. They will consider the content. So, your decision should be based on this question: Can he provide content that will help sell you to the Admissions Committee? Because this is your only professional full-time employment, you may need to use him.
I recall receiving a letter of recommendation written by an elderly man, and scribbled on an odd size of note paper. At face value, you may think this would look very bad for the applicant. However, this recommender told a poignant story about how the applicant helped him run his business and created changes that very important for the continuity of the business. It was of high value to the admissions process.
Conversely, I've received letters from former Presidents (of the U.S.) that said, "I know this young man's family and they are great supporters of my campaign. They are good people and I'm sure he is as well." Guess what? That letter - despite it coming from a former President - carried a negative value for the Admissions Committee. Why? The candidate went for a "glamour" recommender, who clearly did not know him, and could not speak to his professional performance.
- If you don't want to use your current supervisor, this is easily explained (and be sure you do explain it) to the Admissions Committee as not wanting to jeopardize your current employment (as noted by JonAdmissionado).
- Who else can provide a reflection of your professional performance and potential? Clients? Vendors? Community leaders who you've worked with on a significant volunteer role?
I hope these observations are helpful to you. Just remember - who you select as a recommender reflects your professional judgement. Demonstrate good professional judgement!
Let me know if I can help you further.