The true measures of a pitcher are his peripherals (K%, BB%, GB/FB etc). ERA incorporates too many things that are outside a pitcher's sphere of influence (Strand Rate, BABIP, official scorer's decisions, quality of his team's defense, umpiring).
If your survival was based on your ability to predict which pitchers will perform best in the future you would be wise to make your picks based on peripherals rather than ERA. You would live much longer that way.
There are quite a few peripheral-based stats that predict future ERA better than current ERA does.