Are Rendon's 2015 injuries slowing progress this season?

The Nationals offense has not had a moment yet where more than a handful of players were hitting at the same time.

Bryce Harper started off well. Wilson Ramos is surging now. Daniel Murphy has been consistent throughout.

But other key pieces like Jayson Werth and Ryan Zimmerman haven't gotten into a groove yet at the plate. They have certainly had their moments, just not the day-to-day consistency up and down the lineup the team will need to really get rolling in the National League East.

And the top of the order has not supercharged the big bats that come later in the lineup by getting on base as much as they would like.

As my colleague Mark Zuckerman wrote this morning, Ben Revere hasn't been hitting much since his return from a strained right oblique.

Surprisingly, No. 2 hole hitter Anthony Rendon has not been able to get going in May and his slugging numbers are down, with just nine extra-base hits in his first 150 at-bats of 2016.

His current slugging percentage of .313 is down from his breakout season of 2014, when it was a robust .473. His on-base of .314 and slugging of .313 are career lows, albeit in a very small sample size.

It got to the point Sunday where manager Dusty Baker made the unusual move of pulling Rendon late in the game for Murphy as a pinch-hitter. Murphy had been scratched from the lineup due to illness.

Baker said they went with Murphy because of Rendon's recent scuffles. Rendon was 1-for-4 on Sunday with a strikeout and three men left on base. Baker also wanted to somehow get Bryce Harper one more at-bat.

But with two outs and two men on in the bottom of the ninth, Murphy flew out to center to end the game.

"Rendon hasn't been really driving the ball yet," Baker said "In that situation, I was hoping ... that guy (Marlins reliever A.J.) Ramos, he's tough. Right-handers are hitting .138 and left-handers are hitting .148. So I went with him there. You're going with a .400 hitter vs. a guy who right now is hitting .220. And if he gets a hit, I was trying to get Bryce to the plate."

So does this mean that Baker is a bit concerned with Rendon's start through the first 40 games of the season?

Baker said hitting coach Rick Schu and assistant hitting coach Jacque Jones believe they have found out why Rendon is not driving the ball as he normally does.

"Rick Schu and Jacque and him are constantly trying to find out what the problem is," Baker said. "It's just right now, it seems like he's not getting the bat head out front. We know Anthony can hit. Everybody knows Anthony can hit."

Baker also pointed to Rendon's injury-plagued 2015 campaign, when he missed the beginning of the season and finished up with only 80 games. He wasn't activated until June 4 last year after suffering a left knee MCL sprain in spring training. But just 21 days later, he suffered a left quad strain that kept him out until July 25.

"You miss as much time as he's missed last year, he's got to find his groove again," Baker said. "We know Anthony is going to hit, big time."

That is one of the keys to making this lineup potent from top to bottom. Especially with all the walks that Harper has had to endure, if Revere and Rendon are clicking, opposing pitchers will be less inclined to give Harper a free pass.