Answer the question
There are a number of things to take into consideration with your question Mike. I took a shot at it in an earlier post, but let me expand some.
The main issue here is the "Objective" evaluation. The joker in Daves post may get the promotion due to being owners son, my drinking buddy or is expecting a new kid and needs the money. That is the subjective evaluation, based on my (the managers) opinion. So each of these employees have been at the job 1 year and no one stands out, they have all been automotons only doing what they were told and how they were told to do it. If it wasn't for signing off on their time cards the manager wouldn't even know they existed. In that case then eeny, meeny, miny, moe would work, it may also be why the supervisor is leaving in the first place, they're not needed.
In the last year have you not evaluated them, their capabilities, their promise, their drive, their dedication, their reliability, their attendance, ability to work as a team, leadership ability, etc. etc.???
Here's the meat and potatoes. What have you evaluated them against? Each other, industrial standards, your performace?
Attendance, black and white. Absent or not, excused or not excused, advanced notice or last minute. Now add this into it, is s/he a drinker? may be the last minute call is due to a hangover your've smelt booze on their breath before! or
HE is calling in because his child is sick and he needs to stay home. Do you look at that situation differently than say when a female calls in?
So how do you evaluate there dedication? Because they show up each day on time? Take the over time when offered. How about the guy that doesn't work over time do you dock him for not taking it when offered? May be his dedication is with his family or he may be taking classes at night and just hasn't said anything.
All I'm trying to show here is how easy our subjectivity and prejudices can sneak in on our "appraisals".
So who would I promote and how would I decide. After a year I would know who could handle the job. I would give them opportunity to show leadership (lead a CFT, improvement suggestions, etc.). It can not be based on a yearly sit down and talk. If that's all it is I've failed as a manager. My supervisor should have been training to take my job and their subordinates should have been training to take over as supervisor. It's done on a day to day, weekly, etc. basis. Looking at performance in different situations, allowing decission making to take place and providing consistent and constructive feedback and training.
I look at it this way, when evaluating overall performance I am also evaluating my performance as their mentor. I should not hold them responsible for my failure (over looked training oportunity, didn't allow them to show leadership skills, etc.). They can't be held responsible, but they do suffer the consequences by missing the promotion.