Is a fielder blocking an opponent's view against the rules?

Years ago Bobby Valentine when managing the Mets (1996-2002) sometimes had his first baseman stand between the runner on first and the bag so that if the pitcher threw to first, the runner would have to go around the first baseman to return to first base. Maybe not brilliant but certainly clever, a trait that Valentine embraced about himself.

Fielder in front of mound. Wednesday, April 18, 2018

There may be times when it makes sense to put a fielder in front of the mound:
- protect the pitcher
- actually field balls
- block the batter's view of the pitch.

Face guarding, the ultimate shift. Sunday, May 8, 2016
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It makes a lot of sense. But unlike professional football and basketball, the major baseball league has little patience and less imagination regarding things that might breach protocol, real or imagined.

Sunday, April 22, 2018
Start Time: 3:10 p.m. ET
Attendance: 48,137
Venue: Coors Field
Game Duration: 3:47
Day Game, on grass
Cubs 10, Rockies 9

Javier Baez introduced common sense near second base in that game. In the first inning Cub third baseman Kris Bryant froze at the plate and was Hit by Pitch in the face. Baez is the Cubs second baseman but in this game Baez started at shortstop. The Cubs scored three runs in the first inning and Baez hit a home run in the second inning so Baez might have been a little full of himself. He's been hitting very well all season.

In the first inning Colorado leadoff hitter DJ LeMahieu was safe on an error by Baez and then LeMahieu stole second while Colorado center fielder Charlie Blackmon was batting.

In the bottom of the third inning LeMahieu was safe on a ground ball fielder's choice. Blackmon then singled LeMahieu to second.

With Colorado third baseman Nolan Arenado batting Baez thought that LeMahieu was trying to interpret the signs by the Cub catcher to the Cub pitcher. A runner on second has a clear view of the signs. Everyone knows that. It's called sign stealing.

Baez took unusual action. Baez moved in front of LeMahieu in order to block LeMahieu's view of the signs. Baez would then return to normal shortstop position after the signs had completed. Remember, both are second basemen. LeMahieu took exception. The following MLB link contains a two minute video of the incident. Also note that narrative states that the umpire told Baez he had to "get out of the way before the pitch was released". Really? What the heck? Who knew? Note also that before one pitch Baez runs to second base and takes a pickoff throw from the pitcher. LeMahieu gets back safely.

Baez, LeMahieu explain spat at second base
LeMahieu denies Baez's allegation of sign stealing
By Owen Perkins Special to MLB.com April 23rd, 2018

... Baez started using his body to block LeMahieu's view of catcher Victor Caratini, whose signals, Baez claimed, were being relayed by LeMahieu to Arenado.

Baez had never tried the tactic before, but he had seen it used against Puerto Rico in the World Baseball Classic...

LeMahieu denied stealing signs in a text to MLB.com's Thomas Harding...

... Baez felt the Rockies were using their opportunities to hit Cubs pitching in the Rockies' 5-2 win Saturday, and he didn't want to see it again Sunday...

Second base umpire Vic Carapazza had to intervene, and some players and coaches stepped in to make sure things didn't escalate.

"He was trying to get us out of it," Baez said of the umpire. "He was doing his job. He told me I have to get out of the way before the pitch was released, which I was doing. So I don't know why he was so hyper saying that.

"It didn't get me out of my game. I don't know what it did to them. It's part of the game."

The tension between Baez and LeMahieu rose after Arenado struck out while Baez effectively blocked LeMahieu's view of the catcher. Baez gloated a little to his teammates and wasn't shy about letting LeMahieu hear him.

"Right after the strikeout, I said to the outfield, 'You see the difference when they don't know the signs?'" Baez said. "And then [LeMahieu] said something. … We won the game, and the series."

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Cubs' Joe Maddon On Javier Baez's Blocking Of Sign-Stealing: 'Who Else Would Do It? He Has The Balls To Do It'
"All this stuff is part of the game," Maddon says.
BERNSTEIN & MCKNIGHT SHOW APRIL 24, 2018 - 12:15 PM

Two days after Cubs infielder Javier Baez beefed with Rockies second baseman DJ LeMahieu over attempted sign-stealing Sunday, Chicago manager Joe Maddon called Baez's tactic to stand in front of LeMahieu to block his view toward home plate "brilliant" and expressed his belief that, of everyone in the big leagues, of course it would be Baez who made headlines with the ploy.

"Who else would do it?" Maddon said on the Bernstein and McKnight Show on 670 The Score on Tuesday. "Who else would do it?

"Because he has the balls to do it, quite frankly. I mean, there's a lot guys who would never do that. I think you're going to see it become more prominent now that he's broken the ice. He said that (Andrelton) Simmons did it in the (World Baseball Classic). I talked to him yesterday on the off day, and I thought, 'Man, that is really good.' I never thought of it. I'd never thought of it. Actually when he was doing it the other day, we were yelling at him, 'Get back, get back.' We thought he thought something else was on. But he was just doing what he thought was the right thing in the moment. I love that he's fearless. I love that he's saying, 'Hey, this our team. This is our game. This is how we're going to do it.' At the end of the day, if you're the runner at second base, understand that you're trying to steal signs, we have every right to try to conceal our signs."
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