it depends on your goals bro.
someone who is a gym rat and only lifts weights will be good at lifting weights. but put them in a legit bikram yoga class for 90 minutes and they will tap out after 15 minutes tops.
that is what triathlons are the hardest competitions in the world, you have to be good at swimming, bicycling, and running. if you suck at 1 or 2 of those you will be screwed