The Vikings marathon preseason has concluded. A five-game exhibition schedule that began on August 9 in Canton, Ohio at the Hall of Fame Game ended in Nashville, Tennessee with a 24-17 victory. Along the way, the Vikings took many steps forward as they prepared for the 2015 regular season, including some positive moments even in the loss to Tennessee.

Here are five takeaways from Thursday night's loss to the Titans, the first preseason loss in nine games under Mike Zimmer…

1. Heinicke impresses againUndrafted rookie QB Taylor Heinicke had been quietly impressing during the Vikings offseason program and training camp. But then came the preseason, and Heinicke got on the field for everyone else to see. On Thursday night, Heinicke started and finished the game. He finished going 27 of 41 for 279 yards with 2 TDs and 0 INTs for a passer rating of 101.6. He was under duress on many of his dropbacks and wasn't afraid to deliver in the face of pressure and take a hit. He was judicious about when to leave the pocket, but when he did take off he made it count (2 rushes for 21 yards). He made good decision after good decision, and capped an impressive several months with an inspiring performances against the Titans.

2. Reserve defensive line was disruptive, tooThe Vikings defensive line has received rave reviews every step of training camp and the preseason. And even with none of the starters plus Tom Johnson in action on Saturday night, the defensive line was still disruptive. DE Justin Trattou was winning at the point of attack consistently in both the pass and run game. Fellow DEs Scott Crichton and Danielle Hunter were around the QB a bunch, too, and Crichton received credit for 1.0 sack; Hunter also registered a special teams tackle. Those three DEs showed they each have some juice pressuring from the edge and the depth at DE will make it interesting to see how GM Rick Spielman and head coach Mike Zimmer decide to shape the defensive line over the weekend when they cut the roster from 75 players to 53.

3. Some young defensive players got extra workMost of the Vikings projected starters didn't see the field on Saturday night, but there were at least two potential starters and two more key reserves who were given reps. S Robert Blanton started the game and so did Gerald Hodges. Blanton is the returning starter at his spot and has remained atop the depth chart all offseason and preseason, but the coaching staff decided to give him a couple series of action. Hodges started at Mike LB for the first time last week in Dallas and it wouldn't be a surprise to see him line up there next Monday night in the regular season opener, but he also started the game at his position. A pair of rookies who are expected to contribute regularly on defense during the regular season saw significant action in the finale of the preseason – LB Eric Kendricks and CB Trae Waynes. Both players were active in the game, with Kendricks collecting 3 tackles and an assist on special teams and Waynes putting a jarring hit on a ball carrier in the run game.

4. Diggs keeps making playsIt's likely at least three others will see more action this season, but there may not be a Vikings rookie who has impressed more frequently than WR Stefon Diggs. It seems he makes a highlight reel catch every practice and he's also found a way to contribute in preseason games. But Thursday night in Nashville may have been his best all-around showing. He was targeted by Heinicke 9 times and came down with 8 receptions for 85 yards and 1 TD. He also had a 29-yard punt return. Every time he steps on the field, he just finds a way to make plays.

5. Several stand outs on special teamsFor good reasons and bad, there were several standouts on special teams from Saturday night's game. Unfortunately, Marcus Sherels mishandled a punt and turned it over. K Blair Walsh also missed another FG try, this one from 48 yards. And P Jeff Locke had a touchback. The good news is that Diggs ripped off that 29-yard return, the Vikings allowed zero punt return yards, LB Michael Mauti blocked a punt late in the game, Hunter showed up with a special teams tackle and Locke put another punt inside the opponent's 20. When it comes to Locke and Walsh, the Vikings know both can play at a high level. So it's not a question of "Can they do it?" It comes down to fixing the flaws and getting back to that high level of play (Walsh a 2012 Pro Bowler) in time for the season opener next Monday night.