In my opinion university ranking has the least effects on strengthening research capacity. in fact the stimulation, hardworking and enthusiastic manner of each student are the most influential factors. i see a lot of students who are studying in low ranking universities however they are rich and have deep research background.
University ranks are assigned based on cumulative performance (measured, perceptual and other scores depending on which ranking you have in mind) of teaching-learning process, research, students' learning outcomes, outreach, governance and several others. Each ranking assigns a different weight to each of these components. Thus, the ranking is a post-facto number assigned for the university in a specific year.
Based on these ranks, Government agencies or private agencies allocate funds for research projects taken up by the university. Better the rank, higher is the probability of getting more funds for research - ranking helps in attracting funds, which in turn attracts high caliber research talent to work in such projects. The strengthening capacity of university rankings lies in this context.
To be frank, nowadays, all rankings are not objective. Very few are genuine and stood the test of time. Others just run the exercise as an established custom.
Actually students and research scholars get confused by different rankings assigned to one university by different agencies.