This isn't 1970. We know a LOT more about what makes a good player than batting average and fielding percentage.
Batting average of course ignores such things as on base percentage and slugging, as well as base stealing, etc. as well as viewing it in context of what the league is doing (offense is up now, for instance) and the home park differences. OPS+ isn't perfect, but vastly better than BA on it's own - and Puig's career OPS+ is 122 vs Martinez's career 120. Oh, and Puig is the younger player. Generally when players come up late like Martinez their peaks tend to be short, and they decline quickly.
Yasiel Puig
Jose Martinez
Using fielding percentage is ridiculous. What matters is getting to the ball and making outs. There are services that actually analyze what players actually did on the field to get the other team out, as opposed to the "official scorer" who is doing another job also, checks on his box on whether the player blatantly screwed up. I.e., errors are where the player touched the ball and then screwed up, while if the player didn't get to the ball, it doesn't count as an error - but a statue doesn't get to balls that other players would routinely. For his career, Puig is listed as 40 runs above average in actually saving runs defensively. He makes some throwing errors, but also makes a LOT of throws the average player wouldn't even attempt. Martinez just doesn't do much, costing his team 22 runs compared to an average player. In other words, he might be a nice guy, but he is a bad fielder.
This is irrelevant, of course. When Puig stopped being an all star caliber player, the Dodgers dumped him for two prospects who are now two of their top prospects, and haven't missed him. I doubt that the Cards miss Martinez - with his fielding he has to be a top hitter to be valuable, and he isn't. Oh, and he's actually a year and a half older than Puig. Hitters who don't hit the majors until 27 rarely have long careers, and tend to decline rapidly. Getting a nice prospect for him is a steal.
As an outfielder, Martinez kept