Developing adequate plate discipline is an important part of a young player’s growth as a hitter. This does not necessarily mean that just learning to take a walk is the key to success; the ability to pick up on whether a pitch is a ball or a strike, and learning which of those pitches you can and cannot do something productive with, is just as imperative. Today, we’re going to take a look at a few players who saw significant differences in their plate discipline from 2007 to 2008, and whether we can expect them to repeat their success going forward.

There are a few different ways to measure plate discipline, but for the purposes of today’s exercise, we will mainly be taking a look at the percentage of pitches swung at outside the strike zone, as well as contact percentage.

B.J. Upton‘s 2008 season may appear disappointing at first glance-especially when compared to his ’07 campaign-but there were plenty of little things to like that should intrigue fantasy owners as the new season approaches. Let’s ignore for a moment the drop in power production; this was caused by an injury to his left shoulder that was taken care of by an off-season surgery. What we end up with is a player who improved his walk rate by bumping it up a few percentage points, while also dropping his strikeout rate significantly from 32.5 percent of his at-bats to just over 25 percent.

Upton managed this by chasing a lower percentage of pitches that he couldn’t do anything with that were outside of the strike zone. After swinging at 19 percent of pitches outside of the zone in ’07, he dropped to 15 percent last year, closer to his 2006 numbers when his strikeout rates weren’t quite so obscene. The difference between 2006 and 2008 however, is that he made contact with far more pitches that he did swing at outside the zone, jumping from 46 percent last year to nearly 67 percent in 2008. That’s not anywhere near the league leaders in that rate, but it does put him in the top third of the league among those with a minimum of 350 plate appearances, whereas last year’s figure would have put him near the very bottom of the rankings.

Upton’s contact on pitches in the zone and his overall contact percentage also rose, though not as drastically. These signs all point to Upton having a monster campaign in 2009, as long as his shoulder is healed and no longer a hindrance to his power. Assuming that he recoups some of his fly-ball tendencies from 2007, a more patient and disciplined Upton is a scary proposition for opposing pitchers, and one of the reasons that you should be falling all over yourself to draft him.

Teammate Dioner Navarro also saw some changes to his plate discipline last year, though in a different way. While his approach did not change that much, the results did; Navarro’s .295/.349/.407 line is easily the best he has posted during his major league career. Navarro didn’t swing at many more pitches in the strike zone or out of it, but he did see a minor jump in his contact rate on pitches inside the zone, and a huge leap for those out of it (57.8 to 71.7 percent).

Navarro also saw a lower rate of first-pitch strikes in 2008, with 52.8 percent thrown against 2007’s 58.8. Considering that he hit .170/.211/.273 after a count of 0-1 (in 205 plate appearances-he saw a lot of first-pitch strikes), that’s probably a good thing, though he also handled them much better in 2008 (.303/.325/.455). He was also a better hitter with two strikes, posting a line of .238/.284/.331 in 194 plate appearances, against 2007’s brutal .127/.185/.259 (179 PA) showing. This is where the added contact comes into play, as Navarro did a much better job of keeping his at-bats alive and doing something productive with them. Further evidence of this comes from his strikeout rate, which fell from 17.3 percent to just 11.5 percent. Before 2008, Navarro was a hitter who struggled to maintain a consistent level of production, mostly due to his inability to fight back once he fell into a hole in the count. He’s just 25 years old, and we’ve likely witnessed significant growth in his ability to combat this issue. He should be a very good pick at catcher this year, even without considering the benefits of his being in the Rays‘ lineup.

Andre Ethier had the most impressive season of his young career last year, bumping up both his batting average and his power while logging a career high in plate appearances. He did this by being a more patient hitter, swinging at fewer pitches out of the zone (25.7 percent, down from 33.1) as well as inside it (74 to 63 percent). His walk and strikeout rates did not change much despite this significant shift, one that saw him jump from 3.7 pitches per plate appearance to 4.2 (tying him for seventh-best in the majors). His power received a boost though, and his previously consistent Isolated Power crossed the .200 mark for the first time.

His newfound patience could very well be at the root of two developments in his batted-ball data. First of all, Ethier hit fewer fly balls last year, but posted the highest HR/FB rate (14.1 percent) of his career. Secondly, though normally a solid line-drive hitter, he was well above the average last year, enough that his .336 BABIP does not look out of the ordinary. Now that he’s entering the magical age-27 season, we may see a repeat or an even better performance this year. PECOTA certainly thinks that his tweaking his plate discipline was for the good, as his forecast calls for a .292 EqA with some excellent projections above the weighted mean.

Rick Ankiel surprised many by being as productive as he was in 2007, but even more unanticipated may have been his 2008 season, when he took a few steps toward becoming more of a legitimate force at the plate. He stopped swinging at as many pitches outside of the strike zone (from 37.2 percent to 30.4) and displayed more patience overall, with his P/PA moving from 3.4 to 3.8; not that impressive of a number on its own, but an improvement on the 3.4 that ranked near the bottom of the league among qualifiers, way down in Carlos Gomez and Garret Anderson territory.

This resulted in additional walks (he walked unintentionally in 6.8 percent of his plate appearances in ’07, and increased that to 9.1 percent last year), and for a time, fewer strikeouts. Up until he strained his abdomen in late July, Ankiel had been hitting .282/.347/.543, while whiffing 23 percent of the time. After the injury and playing part time, Ankiel struggled, posting a .169/.286/.308 line with 20 strikeouts in 65 at-bats. His batting average should have been higher than it was, which would have made his line look that much better, but as it is, we have a player coming back and refining his approach with additional experience against major league pitchers, and succeeding while doing it. While the question heading into 2008 was whether or not Ankiel would be able to repeat his initial success, the question now has more to do with his health-if he can stay on the field, we know he’ll produce at a high level.