Defense
The Nationals did not rate well last season defensively, posting minus-44 defensive runs saved as a group. Aside from Anthony Rendon, Taylor, and Turner, the rest of the team was average at best in the field. Moving a healthy Eaton to left field full-time should help, but the Nats will probably still be middling on defense in 2018.
Los Angeles and Chicago both feature elite defenses with top-notch gloves scattered around the field. In L.A., the Dodgers boast Corey Seager at shortstop, Cody Bellinger at first, and Justin Turner at third, with a bevy of talented outfielders behind them. Chicago can match them step-for-step, with Kris Bryant, Addison Russell, Javier Baez, and Anthony Rizzo forming one of the best defensive infields in baseball.
Milwaukee, St. Louis, and Arizona also have upper-level defenses that could provide them with a couple extra wins in a potentially tight NL Wild Card race.
San Francisco is the only potential contender who played defense as badly as Washington in 2017. Offseason additions Evan Longoria and Andrew McCutchen are still decent defenders, but they just add two more aging veterans to a roster already filled with them. Six of the eight projected starters will be over 30 years old on Opening Day, which might kill a pitching staff that struggled in 2017.