One of the few bright spots at wide receiver in Week 1, Keenan Allen ended up having a career day setting multiple records in a 33-28 home victory.

Allen was targeted a league-high 17 times, hauling in a franchise-tying record 15 receptions for a personal career high of 166 receiving yards.

Not a bad start to the season, right?

But are these types of outings sustainable for Keenan Allen as he tries to bounce back from a disappointing 2014 campaign?

No -- and I'll give you four reasons why not.

1. Unsustainable Volume

Philip Rivers' 42 passing attempts last Sunday shouldn't be thought of as a common occurrence. Rivers surpassed that total only twice last year and only five times over the past two seasons combined. The Chargers have been one of the more balanced teams over the past two years, passing on only 55.8% of their plays. This sheer volume that Rivers dropped back to pass in Week 1 isn't a common occurrence and can't be counted on as weekly source of volume.

Allen was able to haul in 15 receptions, tying a franchise record with Kellen Winslow and marking only the third time in his career Allen has had double digit receptions. Only Jason Witten and Wes Welker have been able to top 15 receptions over the past five years, a surprisingly rare accomplishment in today's passing league. None of the other typical "top tier" receivers have accomplished this feat in recent history, and it would be surprising to see Allen come close to this performance again.

Nearly half of Allen's 166 receiving yards were almost all after the catch, as his 81 yards after catch (YAC) led all wide receivers. Looking at this in a vacuum, you could say that both Allen and the lack of tight defensive coverage contributed to such a high output. But teammate Stevie Johnson was right behind him ranking second in YAC as 79 of his 82 receiving yards were after the catch as well! This should instead point to terrible execution by the Detroit Lions defense and good in-game adjustments by head coach Mike McCoy.

Allen has rarely shown a penchant for having the "big game." As Dan Pizzuta noted in an earlier article about Allen's 2015 rebound potential, Allen's 100-yard outings fell from five in 2013 down to only three in 2014. At the other end of the spectrum, Allen's rate of "low games" -- games in which he had less than 30 receiving yards -- rose from three in 2013 to five in 2014. While part of his poor 2014 campaign may be contributed to injury, this downward shifting of both his ceiling and his floor is worthy of note as Allen's receiving volume has been unreliable throughout his career to date.

2. Unreliable Target Overload

A whopping 17 targets found their way towards Allen, as Rivers routinely made him his favorite target of the day.

Allen was able to lose Rashean Mathis with ease regularly as he burned past the 35-year old cornerback, making play after play. Unfortunately for Allen, he won't be lining up one-on-one against too many 35-year-olds this season.

It's also not too hard to rack up the yards after catch when given these kinds of opportunities left unmanned.

Allen utilized the short passing game to near perfection with Rivers as his average depth of target (aDOT) was 5.5 yards per ProFootballFocus, ranking 83rd of the 103 receivers to see a target in Week 1. Rivers continually hit the underneath route all day (Stevie Johnson's aDOT was 0.5 yards) as his receivers overmatched the Detroit secondary leading to an abundance of targets.

11 of Allen's 17 targets came within the 5.5 yards aDOT, as San Diego implemented a large number of shallow crossing patterns. Seeing an additional two red zone targets come his way, Allen was able to haul in both but fell short of reaching the end zone both times.

While targets are a great foundation for fantasy purposes as pointed out by 4for4's Chris Raybon, they need to come from a reliable source that you can count on week to week. 17 targets by a wide receiver is an obscene amount that was topped only three times last season. This unreliable number of targets is hard to forecast repeating with any conviction for Allen in any future upcoming games, as he saw an unrepeatable target overload in Week 1.

3. An Incredulous Target Market Share Percentage

Before you start pursuing any potential trade offers after missing your man on the waiver wire, don't talk yourself into trading away a valuable commodity like A.J. Green to try and get a piece of the Allen pie.

Allen saw the highest percentage of his team's targets (40.5%) this week out of all wide receivers. Last year he saw only 21.1% of the team's market share. To provide some context, last year only Demaryius Thomas and Andre Johnson eclipsed the 30% mark, so this 40.5% mark is almost comical. This seismic shift was what buoyed the rest of Allen's stats as he saw a ridiculous amount of targets -- and cashed in on the associated productivity that comes with it.

The problem is Allen won't always be getting these looks. Antonio Gates is only three games away from returning, and the offense could see both he and Ladarius Green getting more looks after an impressive 5-catch, 74-yard, 1-touchdown outing by Green. Gates saw 99 targets last season and Rivers will likely turn back to him more often as a short safety valve given their long tenured history together.

Gates has also been the more efficient of the two playmakers on a per-target basis over the course of their playing time together. According to our Target Eddie Royal had a better Target NEP score (79.86) over his last two seasons with the Chargers than what Allen had compiled.

Allen may have had a meteoric percentage of the team's target market share in the opener, but don't expect it to last. Especially with Gates' return looming in the not-so-distant future.

4. You Can't Rely on This Game Flow Weekly

The Chargers trailed by an early 21-3 deficit before coming back scoring 30 unanswered points. No matter what team, scoring 30 unanswered in the National Football League is not an easy feat to accomplish.

Aside from big returns and defensive plays, that kind of deficit can be made up only by passing the ball an obscene amount of times (Reason #1 listed above) and heavily targeting your top receiver (Reason #2) in abundance (Reason #3). San Diego ran 74 plays last week -- second most in the league -- as they furiously mounted a comeback. This type of volume is hard to rely on week to week when trying to predict the game flow and how the offense will play out.

Three turnovers -- including an early pick-six by Glover Quin -- were one of the main reasons for this nose dive in game flow. Rivers threw another pick on a 1st-and-goal opportunity that negated a well orchestrated drive. Rookie Melvin Gordon was introduced to the NFL by the Lions defense as they forced a fumble and recovered when San Diego was on Detroit's side of the field. Poor decisions and miscues led to the Chargers having to revamp their attacking style and alter their game plan.

The Chargers ranked in the bottom half of the league the last two years in turnover giveaways, as they've done a fairly decent job protecting the ball. You simply can't rely on the Chargers having to dig themselves out of holes on a week to week basis.

Conclusions

I understand that we're all excited that football is back, but take a breath and process how and why Allen looked so great.

He was one of only six receivers that surpassed 100 receiving yards in Week 1 giving the illusion that he's returned to top form, when in reality he's sharing that same honor with the likes of Nate Washington and Kendall Wright.

In a week where nearly all of the league's supposed "top tier" receivers fell flat in their season openers, take a moment -- breathe -- and don't let yourself get caught up in the hype.

Enjoy the 31 fantasy points Allen got while running circles around old-man, uncle Reshean -- just don't be surprised if Allen already hit his fantasy ceiling for 2015.