YASNY, I have a small disagreement with you on this. The problem I have with career stats as they do not always reflect the guys current condition. Extreme example Take Shamee pre-"working out" and post "working out" power numbers. Factor in career and it lowers what you could reasonably expect from him. IT also doesn't take into consideration the age of the player. Career stats for a 30 year old may be a better reflection in his next 5 seasons than career stats on a 40 year old.
I try and see some trends in the numbers. Know what you are looking at (as you do)and draw reasonable conclusions based on the appropriateness of the stats. Career stats may or may not be a good tool to judge the future performance. It depends on the individual. The previous 2-5 years may be an even better tool. Sometime you need a hammer, sometimes a wrench. Each tool is different, just as each stat is different.