How can I better deal with position papers?
Writing position papers does not require any special innate talent or disposition. You can develop these skills through the combination of systematic method and frequent practice.

First, you need to understand that a "position paper" (a.k.a. "analysis paper") is very different from a "survey paper" or an "essay".  A position paper is somewhat similar to a legal argument for each side of the question.  Your only goal is to communicate and evaluate the arguments for and against each alternative.  You don't have to describe the whole issue, its history, its cultural setting or social significance, or many other issues. Deconstructing the question or alternatives is not in-scope for a position paper.  Neither is your impressions, experience, or personal value judgments.  Don't go "meta".  (Those are in-scope for an essay.)

Here's the method, boiled down to its essence:


Be clear about the scope of the question and alternatives. Make
assumptions if you have to fill in blanks.
Identify an ideal advocate for each alternative or position, even if you imagine a fictionalized advocate.
For each alternative and idealized advocate, make an outline of the following:

Their strongest argument in favor of that alternative
Their strongest argument against the other alternatives
Their counter-arguments to the criticisms of the advocates of the other positions

Once your outline is complete, rewrite it in sentence and paragraph form.
Finally, add introduction paragraphs setting up the debate and conclusion paragraphs that evaluate the relative strengths of the various arguments.


From your professor's point of view, the most important paragraphs are the conclusions where you decide which of the arguments is most compelling and with the least number of unanswered flaws or voids. 

In your example:


  Learner-centered approaches should replace teacher-centered approaches


Who best advocates learner-centered approaches?  Who best advocates teacher-centered approaches?  What arguments do they advance to support their positions?  What criticisms do they level at the other?

In examining these arguments, the following questions might come to your mind to compare and contrast the positions: Do they both agree on the criteria are for "best" or "better"? Whose values and needs are most important? Do they both agree on what the implications are for "change" vs "status quo"? 

What evidence does each advocate have to support their position?  What credibility and relevance does the evidence have?  What are the uncertainties and voids (lack of information) in each position.  (No argument is perfect or free from some uncertainty.)



The best way to learn this is to practice it frequently. The best way to practice it frequently is to start a blog and write a post every day or every other day on a topic area that is important to you. Aim for 'minimalist' position posts, which are probably four paragraphs.

After you do this for a couple of months, you will find that you are no longer seeking your professors' feedback regarding whether you are giving them what they expect to see.  Your confidence and efficiency will rise.