I'm sorry, are you being serious or intentionally snotty here? They appear because they are a stat people do care about. But it's really easy to imagine scenarios as to why W/L aren't all that helpful. Take, as an example: Pitcher 1: 7 IP, 6ER, 4BB, 8 Ks Pitcher 2: 8 IP, 1ER, 2 BB, 9Ks I think we can agree who had a better start. Now what if I told you pitcher 1 took the win because his team scored 10 runs and Pitcher 2 lost because his opponent hurled a shut-out? This happens all the time with wins and losses and I haven't even mentioned how bullpens factor in. So, no, wins and losses are not all that valuable for assessing a pitcher's success.