The old saying that a series doesn't start until a team loses at home doesn't apply when it comes to the second-round set between the Golden State Warriors and Houston Rockets. After the defending champs won both Game 1 and Game 2, there is little doubt that they will soon be moving on to the Western Conference Finals.

Even before the series heads to Houston, it's abundantly clear that the Rockets simply aren't good enough to upset the Warriors. Houston now has to defeat Golden State four times in five games in order to eliminate them from the 2019 NBA playoffs.

James Harden put up historic offensive numbers in the regular season. He's rightfully been praised for averaging 36.1 points on just 24.5 field goal attempts per game in addition to his 7.5 assists and 6.6 rebounds a night.

The playoffs, however, are a different animal. Harden can’t trick the referees like he was able to during the regular season. His style of play and high usage rate don't work nearly as well against an elite defense over the course of a long series.

Most importantly, Harden simply doesn't raise his game in the playoffs the same way the all-time greats do.

After missing much of the first quarter with an eye injury, Harden shot well in Game 2 with 29 points on 19 shots in Tuesday’s 115-109 loss at Oracle Arena. The likely MVP runner-up wasn't as efficient in the series opener when he missed 19 of his 28 field-goal attempts.

Harden is shooting 37.7 percent from the field and 33.7 percent from three-point range in this year’s playoffs. Both of those numbers are well below his regular-season averages. That's nothing new for the league's top scorer.

On the heels of last year's MVP season, Harden shot just 41.0 percent from the field and 29.9 percent from three-point range in the playoffs. In the postseason before that, he was a 41.3 percent field-goal shooter and a 27.8 percent three-point shooter.

This is Harden’s fourth chance at eliminating the Warriors in the playoffs since Golden State's dynasty began. He's never shot better than 42.6 percent from the field or 34.0 percent from three-point range in any of those series.

Even last season when the Rockets nearly upset the Warriors in seven games, it was Houston’s team defense that led the way. Harden’s offensive numbers were awfully underwhelming following a strong individual performance in a series-opening loss.

In his last eight playoff games against the Warriors, Harden's average stat line looks like this: 28.0 points, 5.8 rebounds, 5.6 assists and 5.0 turnovers per game. He’s shooting 38.5 percent the field and 22.8 percent from behind the arc on 23.4 shots per contest.

That's not to say Harden has been bad, and he deserves credit for battling through an injury to give Houston a shot in Game 2. But the Rockets need much more from their best player if they hope to get over the hump against this Warriors’ team.

Golden State's vulnerability this season has come from a lack of focus on the defensive end. Houston's only chance to win this series is for Harden to put up offensive numbers that come close to replicating what he averaged in the regular season.

Despite the ups and downs Golden State has faced this season, they still have more talent than anyone with their starting lineup. Kevin Durant is performing like the NBA's best player. Draymond Green looks like an All-Star again. Stephen Curry and Klay Thompson make up the only backcourt that's better than Houston's.

James Harden James Harden is a contender for MVP this season. In this picture, Harden #13 of the Houston Rockets dribbles the ball against the Washington Wizards at Capital One Arena in Washington, D.C., Dec. 29, 2017. Photo: Rob Carr/Getty Images

The Rockets hoped that trading for Chris Paul prior to the start of last season would help them reach the NBA Finals. The veteran’s hamstring couldn't hold up long enough for Houston to defeat Golden State four times in 2018. As good as the point guard can be on certain nights, his best days are behind him in 2019.

Paul is averaging 17.5 points, 5.0 rebounds, 5.0 assists and 4.5 turnovers per game in the conference semifinals. He was largely a non-factor as Golden State pulled away in the second half of Game 2, scoring just four points over the first 22 minutes of the third and fourth quarter.

Houston has been outscored by 36 points in Clint Capela’s 60 minutes. If the Rockets continue to get outplayed that badly when their third-best player is in the game, the series might not even return to the Bay Area.

Game 3 might give the Rockets an opportunity to make this series interesting for a few more days. Golden State has continuously taken their foot off the gas pedal when their backs haven't been against the wall. Maybe Harden will drop 40 points and give Houston a chance to tie up the series Monday night in Game 4.

A barrage of three-pointers could potentially take advantage of a Warriors’ defense that tends to fall asleep at times. The Rockets went 17-40 from behind the arc Tuesday night. Harden’s teammates have been efficient from three-point range this series with 24 makes on 64 attempts.

Once Golden State’s chances are starting to feel a little bit in doubt, the Warriors should turn it back on and take care of business.

The only way for Houston to dig themselves out of this hole is for Harden to play like the elite superstar he often appears to be from October to early April.

Whether it's exhaustion, the difference in officiating or straight-up choking in big moments, Harden has proven throughout his years of offensive dominance that he can't reach the playoff gear achieved by the likes of LeBron James, Kawhi Leonard and Kevin Durant.

As long as that fact remains, this version of the Warriors doesn't have much to worry about.