Reason for optimism: Anchored by the youngest lineup in baseball in 2015, the Astros were one bullpen meltdown away from playing for the pennant.
Reason for pessimism: It might be nitpicking, but the offense wasn't that different than what it was in the darker days of 2013 and 2014.
In 2013, when Houston switched leagues, the Astros ranked 27th in runs scored, last in strikeout rate and 26th/29th/28th in AVG/OBP/SLG. In 2014, those five figures, respectively, were 22nd, 29th and 25th/21st/15th. That's improvement, to be sure, but it's still bottom-third in composite offensive categories.
Last season, in leading the AL West for the majority of the season and ultimately making the playoffs as a wild card, the Astros jumped to sixth in scoring. They must have really changed their offensive approach, right? Well, they remained 29th in strikeout rate, they were still bottom tier in batting average (21st), and they were an improved but still below-average 16th in on-base percentage. The big difference was in slugging, in which they were second in the majors, supported by 230 home runs, the second most in franchise history.