As good as the Nationals' rotation was last season -- it posted the NL's best ERA at 3.40 while yielding the league's lowest batting average at .240 -- the unit was perhaps not as dominant as it could have been for one simple reason.

Davey Johnson rarely let his starters pitch deep into games.

Despite their fantastic numbers, Nationals starters actually threw only the 18th-most innings among all big-league rotations, averaging only 5.88 innings per outing. That's because Johnson let his starter take the mound for the eighth inning only eight times in 162 games.

And all of those starts were made by either Edwin Jackson (five times) or Gio Gonzalez (three times).

There was a clear method to Johnson's use of his staff. With so many young arms in the rotation, he was exceedingly careful not to risk anyone's long-term health.

And that didn't apply solely to Stephen Strasburg, who averaged 5.69 innings per start. The same philosophy was used with Jordan Zimmermann (6.11 innings per start) and Ross Detwiler (5.59 innings per start), two more young hurlers who have yet to be freed from the shackles of pitch counts and innings limits.

Each of those starters, though, is a year older in 2013 (and in the cases of Strasburg and Zimmermann, another year removed from Tommy John surgery). That should open the door for longer starts and higher pitch counts, right?

Well, maybe to an extent. Zimmermann certainly will be allowed to surpass the 110-pitch mark on a more regular basis. (He's done it only once in his career.) But there will still be a leash of sorts on Strasburg and Detwiler, neither of whom has yet to spend an entire season in a big-league rotation.

The leash won't be quite as tight as it's been in the past. Neither Strasburg nor Detwiler will be pulled the moment he reaches 100 pitches or seven innings. But Johnson will still pay close attention to both pitchers' usage and will put more emphasis on their long-term well-being than their short-term chances for a dominant start.