This year, Rendon was rated by MLB.com as the 28th best prospect in all of baseball. Thus far, Rendon has been playing for the Harrisburg Senators of AA. He has a .292/.462/.500 line with 2 HR and 7 RBI in 14 games. And he has a career minor league line of .249/.391/.492 with 8 HR and 19 RBI.
Zimmerman, on the other hand, will be mightly missed. Even with a .226/.311/.358 line with 1 HR and 11 RBI, Zim has a career .287/.353/.477 line with 154 HR and 604 RBI, and has played well, even through the bad of the Nationals.
It'll be exciting to watch Rendon, and if he does well, the Nationals may have a problem. We'll just have to see.