With a brand new season often comes renewed hope in the NFL.

The new regime in San Diego certainly hasn't been immune to this optimism, as they've made it known that they refuse to accept that the Chargers can't rebuild and be a contender at the same time. Although they're well on their way with the rebuild, the jury's still very much out on whether they can win in 2013.

Here's five things that fans should pay close attention to, as they could prove to be integral to whether the Chargers succeed in their plan to kill two birds with one stone this season:

1. The Stopwatch

As I recently wrote, Philip Rivers played at a Pro-Bowl-caliber level when he threw the ball in 2.5 seconds or less last season, despite playing behind an offensive line that ranked second to last in the league. When he held on to it longer than that, he struggled mightily. Therefore, fans should keep a close eye on their handy dandy stopwatches this season.

If the new offense can get the ball out of the QB's hand quicker on a more frequent basis, he could return to his prolific ways even without an improved offensive line. If not, we could be looking at a repeat of last season, which could spell the end of the Philip Rivers era in San Diego. Since nobody wants to see that, keep the stopwatch handy and remember: the magic number is 2.5.

2. Te'o Coverage

No, not the media coverage...pass coverage.

This is where Te'o's predecessors, Takeo Spikes and Demorrio Williams, struggled at times last season. Although Spikes ended up posting middle-of-the-road numbers in coverage, allowing 0.79 yards per cover snap (322 total cover snaps), it sure seemed like he was much worse. Demorrio Williams, on the other hand, was as bad as it seemed, allowing 1.30 yards per cover snap (166 total cover snaps), which ranked second-to-worst in the league.

Fortunately for the Chargers, pass coverage is one area that Manti Te'o really excelled in at the college level. In Chargers GM Tom Telesco's own words:

"Manti was an excellent third-down player at the college level, especially in zones, especially in his football awareness as far as knowing where routes are coming from, knowing where to pass off a route and pick up another," Telesco said. "He has an innate sense of knowing where people are coming from, not only to take on blocks and avoid blocks but as far as pass receivers coming through his zones." Source

Now, the jury's still out on whether Te'o can do it at the NFL-level, as offenses in the NFL are considerably more complex than in college. However, I wouldn't put it past him as he reportedly blew scouts away with his ability in the film room. If all of this translates to the field from Day 1, he could help take this young, up-and-coming defense to the next level.

3. The Demeanor of Ryan Mathews

I'm a big believer in confidence and the effect it can have on a football player - or any person for that matter. It seems whenever Ryan Mathews plays with a confident demeanor, he's shown the flashes of ability that made the Chargers so enamored with him 2010. Unfortunately, injuries and fumbling issues over the last three years have put a damper on that confidence and made him seemingly second guess himself at times instead of believing in that immense ability. Even worse, it has sometimes caused him to fall victim - as many young players do - to the snowball effect, where one mistake leads into another which leads to another and on and on.

There is no season where it'll be more important for Mathews to maintain his confidence regardless of any mistakes than this upcoming one. The new regime in San Diego has no ties to Mathews and thus will be less hesitant to move on from him if he doesn't show that he's worth keeping around.

Mistakes will happen for Ryan. After all, mistakes are inevitable in every walk of life. The key will be for him to not allow that mistake to affect him in a negative way in the future. The best chance Mathews has at success is to play with confidence and trust his natural ability and the skills he's developed over the last three years, no matter what happens. In turn, the best chance the Chargers have at success this season is with a confident Ryan Mathews on their side.

Disclaimer: He'll have to stay healthy, of course, for any of the above to matter.

4. The Number of Dwight Freeney Salutes

In case you don't know, Dwight Freeney's sack celebration is a military salute to the crowd. The hope is that it becomes as regular an occurrence in San Diego as it was in Indianapolis. With the injury to Melvin Ingram and very little depth at outside linebacker, the Chargers don't really have a backup plan, which is risky considering the popular narrative has been that Freeney struggled with the transition to a 3-4 defense last year. The numbers, however, tell a little bit different of a story.

Between sacks (5), hits (9) and hurries (33), Freeney recorded 47 total pressures on the quarterback, which was good for a tie for seventh best of all 3-4 linebackers last season. That's especially encouraging when you consider that Freeney battled a high-ankle sprain for the majority of the season. Could he turn some of those hits and hurries into sacks and double his sack total in 2013? It's certainly possible, but the Chargers will have to put him the right places in order to do so.

One way to get the most out of him would be to get Freeney's hand on the ground - a position he's most comfortable in - as often as possible in pass rushing situations by using the 4-3 fronts that the Chargers have been known to mix in as part of their 3-4 scheme over the years. Another is to not ask Freeney to drop into coverage too often, which is something Indianapolis was effective with last season, as he only played 23 snaps in coverage for them.

The number is five, people.

That's the number of knee surgeries Danario Alexander has had in his brief career - and that's not even mentioning his hamstring issues. Calling him injury prone would be an understatement, which was reflected in the low RFA tender he received from the Chargers this offseason. He needs to prove to the entire league that he can stay healthy for a full season, as he's only played in 28 out of 48 games over his three seasons in the NFL. If he can, he'll turn out to be a major steal and could end up playing the Chargers back in the postseason as early as this year. Check this out.

Player A: 59 RECS, 1098 YDS, 18.6 AVG, 7 TDS

Player B: 59 RECS, 1052 YDS, 17.8 AVG, 11 TDS

So who are those players, you ask?

Player A: 25-year-old Vincent Jackson's numbers for the 2008 season.

Player B: 24-year-old Danario Alexander's numbers for the 2012 season if extrapolated out over the course of 16 games.

Pretty impressive, huh? Especially when you consider that the Chargers picked up Alexander off the street. It's safe to say that they could have a potential gold mine on their hands, but like any gold miner will tell you, it doesn't come without significant risks. Luckily, though, the Chargers will have one more year to evaluate Alexander at a relatively cheap price before deciding whether it's safe to invest in him long term.