The emotions that surround a player’s promotion to the big leagues are intense. Dealing with the realization of a lifelong dream coming true, sharing the moment with friends, family and loved ones, and putting on that uniform for the first time in a 24-hour span takes a special mindset to separate the emotions from the moment. Even veterans still talk about having butterflies on opening day, or the start of a postseason series.

When a prospect gets to the major leagues, they want to do everything they can do to stay there. Sometimes, they know up front they are only up for a specific assignment and will be sent back down at a later date, but everyone gets one chance to make a first impression. Often, that impression is made with the bat and players will try to force that issue.

Josh Donaldson had a successful 2013 season that saw him finish fourth in the AL MVP voting, building upon the success he had late in 2012 as he hit .290/.356/.489 after his final recall from the minor leagues. Donaldson has hit .298/.377/.497 since returning from the minor leagues, which allows many to forget that he hit .154/.172/.246 in his first 130 at bats at the major league level walking just three times. Yasiel Puig’s debut last season generated as many comments about his skills as it did his impatience as he walked just 7 times from his call-up date through the middle of July over 161 plate appearances.

Conversely, you get call-ups like Robbie Grossman with the Astros. Grossman was traded to his hometown team by the Pirates in 2012 as part of the Wandy Rodriguez trade. Grossman made his major league debut on April 24th, and was given 131 plate appearances before being sent back to Oklahoma City. That sample size was enough to look at Grossman’s strikeout rate as well as his walk rate, which were 23.7% and 12.2% respectively. Grossman had posted double-digit walk rates throughout the minor leagues, and his strikeout rate was in-line with what he demonstrated in the minors as well. What did not mesh up with his previous performance was an empty slash line as he hit .198/.310/.243 with just five extra base hits.

Grossman’s .310 on base percentage was due to his willingness to work counts. His 3.72 pitches per plate appearance during his first call-up was better than the likes of David Ortiz, Robinson Cano, and Ben Zobrist during the same time. The problem was that accepting a walk quickly became Grossman’s best chance to get on base, and to his credit, he maximized those chances by swinging at a low 36.5% of pitches thrown his way. Only Jose Bautista swung at a lower percentage of pitches during Grossman’s first call-up (min 100 PA). He returned to Triple-A Oklahoma City in late May and remained there for 226 plate appearances, where he posted a more traditional .265/.374/.368 line with a 14.2% walk rate and a 20.4% strikeout rate. He also made some changes during his demotion.

Prior to his demotion, Grossman had a slightly crouched posture, with a more open stance, and started his swing with his hands level to his chest as shown in the image below from a game in early May.

The changes Grossman made in his stance were quickly evident when he returned to Houston on a homestand in early August against the Boston Red Sox. Here is Grossman at the plate against Boston as he prepares to hit a home run off Ryan Dempster.

There are several noticeable changes to Grossman’s stance at the plate. His stance is more closed, he is closer to the plate and his posture is more upright than it was in May. Grossman’s hands have a higher starting position and his bat starts at a lower angle.

The changes allowed Grossman to hit the ball with more authority, as the average distance on his flyballs increased 13 feet from the first half to the second half and hit 13 extra base hits in 157 plate appearances before being shelved with an oblique injury just after Labor Day. Earlier in the season, Grossman was unable to drive mistakes in the strike zone, such as this hanging 86mph changeup from Anibal Sanchez.

The adjustments to his swing allowed him to take advantage of those types of mistakes with more authority as he did with Dempster’s fastball in early August.

The improved production at the plate led to Grossman becoming more aggressive as he re-gained his confidence at the plate. His walk rate declined dramatically as he became more aggressive at swinging at pitches both within and outside of the strike zone.

Split PA BA OBP SLG K% BB% BABIP Swing% O-Sw% P/PA Apr-May 131 0.198 0.310 0.243 23.7% 12.2% 0.275 36.5% 14.8% 3.72 July-Sep 157 0.322 0.351 0.466 24.8% 4.5% 0.413 44.2% 23.6% 3.67

Grossman’s improvements last season allowed him to make a better first impression the second time around. The Astros believe they have found their starting left fielder for 2014 to add to their growing list of improving young players that are key to their rebuilding process.