1. Ian Kinsler's defensive improvement at 2B. At the beginning of the year, it appeared questionable whether the team could survive his glove at 2B all year. However, by the end of the season he was a consistent and productive glove. With that step forward its easy to see him as a core team member for the next 5-10 years.
2. The Pitching staff in July and August. The team as a whole posted a sub 4 ERA for two consecutive months. That is high enough caliber pitching to get you to the playoffs consistently. That shows that the staff isn't as far away from being the strength of the team.
3. Management being able to pull the trigger on 2 big rebuilding deals. In the past years, this team has been unable, or unwilling, to make rebuilding type deals. This shows a clear view of what the team needs to do to eventually make the playoffs.
4. Salty's Swing. It's a pretty swing, and although his numbers weren't as nice as you'd like, at 22 you can really see him growing into a big time contributor eventually.
5. Rangers got younger players playing time during the garbage time of the season. In years past, especially under Buckethead's reign, we saw veterans who weren't part of the future as the regular starters in August and September. The management showed that they were committed to the future, and showing what they had in garbage time.
Feel free to add any other positives you saw for the future.