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2/24/2014 6:27 P.M. ET

Fister calls playing with Hunter 'a huge honor'

VIERA, Fla. -- Nationals right-hander Doug Fister said it was "a huge honor" to play with Tigers outfielder Torii Hunter, even though the two played together for just one season.

Fister said Hunter is the epitome of a good teammate. Hunter, according to Fister, tried to make everybody around him better. Hunter made everyone believe in themselves and the team.

"Just his presence alone was a huge benefit for us in Detroit," Fister said. "The words that came out of his mouth were even better. On top of that was the example he set on the field. He is a great human being and somebody you can count on as a friend. He is not just a teammate, he is a friend."

Mattheus undergoes MRI for chest pain

VIERA, Fla. -- Reliever Ryan Mattheus hasn't pitched in six days because of chest pain. He had an MRI on Monday afternoon, but the results were not announced.

Mattheus started feeling pain after his bullpen session last Tuesday. While he was doing his conditioning program at the Minor League complex, Mattheus felt a little discomfort, but didn't feel it was alarming enough to call the trainer. Then Mattheus went to Space Coast Stadium to work on his upper body without any problems.

The next morning, however, it was uncomfortable for Mattheus to take deep breaths or to cough or sneeze. That's when he went to see the team trainers.

"[The training staff] thinks it's some sort of strain in there or inflammation, so we are going to get an MRI and figure it out," Mattheus said. "There are a couple of different options they think it could be. I've been down for six days. I could show up [in the next couple of days] and it feels great. I could go back out there and start throwing. If it's something more severe, it might take three or four weeks."

After having a disappointing season in 2013, Mattheus is battling for a bullpen spot this year. He broke his right hand after punching a locker last May in San Diego. When he returned to action, he had a tough time getting hitters out and was eventually sent to the Minor Leagues. After he returned to the big leagues, he still had problems on the mound.

Ramos, Snyder support new collision rule

VIERA, Fla. -- Major League Baseball and the Major League Baseball Players Association have reached agreement on a rule to help protect catchers.

They have negotiated the addition of Rule 7.13, covering collisions at home plate on an experimental basis for the 2014 season. The rule will prohibit the most egregious collisions at home plate. The rule states the following:

"A runner attempting to score may not deviate from his direct pathway to the plate in order to initiate contact with the catcher or other player covering home plate. If, in the judgment of the umpire, a runner attempting to score initiates contact with the catcher (or other player covering home plate) in such a manner, the umpire shall declare the runner out (even if the player covering home plate loses possession of the ball).

"Unless the catcher is in possession of the ball, the catcher cannot block the pathway of the runner as he is attempting to score. If, in the judgment of the umpire, the catcher, without possession of the ball, blocks the pathway of the runner, the umpire shall call or signal the runner safe."

According to catcher Chris Snyder, "If you get a good throw and you have time, it's completely up to the catcher what he wants to do -- if he wants to stay safe, stay in fair territory. If you want contact and block the plate, you get over there and block the plate. But out of everything they could have done with the rule, on paper, this is probably the best-case scenario, I think."

Catcher Wilson Ramos agrees with the new rule. He pointed out that if it was in place in 2012, teammate Sandy Leon may not have been sidelined by injury. Leon, making his Major League debut on May 14 of that year, had to leave the game against the Padres in the fourth inning with a high right ankle sprain.

The Nationals had a 4-1 lead when the injury occurred. The Padres had runners on second and third with one out, when Orlando Hudson singled to center field. Yonder Alonso scored easily, but Chase Headley barreled into Leon to score the Padres' third run.

Leon was clearly in pain and had to be helped off the field by then-assistant athletic trainer Mike McGowan and bench coach Randy Knorr.

Clubs will be required to train their runners to slide and their catchers to provide the runner with a pathway to reach the plate if they aren't in possession of the ball.

"The rule is good [for catchers], because no one wants to get hurt," Ramos said. "It's pretty exciting. We just need to play smart. If we are on the line, we are supposed to get hit. We need to be smart in that situation. ... There are times to move out. It has happened, and we have to understand that. It's a good idea to put in that rule."

Imagine if the rule was in place when Pete Rose collided with catcher Ray Fosse in the 1970 All-Star Game.

"I don't think [the new rule] would have stopped Pete Rose," Snyder said. "The game has evolved. The physique of the player has evolved. It's a different game now. It's faster, it's bigger, player-wise. The rules are in place. In the end, there is going to be contact. It's not always going to be at home plate. There is going to be contact. There is going to be injuries. This is what we do. It's what we choose to do. That's the way it is."

Williams: Harper 'a great student of the game'

VIERA, Fla. -- One thing that has surprised Nationals manager Matt Williams is that outfielder Bryce Harper loves to talk. Harper often comes into the coaches' room to talk baseball.

It would be easy for a young player to go into their own world, but Williams said Harper wants to learn and get better. Harper is known to ask a lot of questions.

"He talks more than I thought he would. He talks a lot," Williams said. "He comes in the coaches' room and sits down and talks the game. I think he is a great student of the game. He pays attention to those types of thing. It's refreshing."

Worth noting

• Nationals reliever Tyler Clippard has recovered from back tightness and threw a bullpen session on Monday. He will have two days off before throwing live batting practice. Like he has in the past, Clippard will start the Grapefruit League season slowly. He will not pitch until the third or fourth game of the spring.

• Infielder Josh Johnson was scheduled to see a doctor Monday because of wrist soreness. Johnson is a non-roster invitee who has been in the organization for four years.

• The Nationals will play their first Grapefruit League game against the Mets on Friday in Port St. Lucie, Fla. Williams said he will "take a little bit of both" when it comes to using the Major and Minor League players on the team.

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He can be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.