Pablo Sandoval GiantsFat Panda. The #LOLFatChat hashtag from LOL KNBR Callers. The GIF of Pablo rounding the bases, looking back at second base, seeing a big piece of cake, and stumbling on his way to third. The Pablo Sandoval Fat Meter, from our friends at McCovey Chronicles.

Pablo Sandoval is a large man. Portly. Big boned. He also has a healthy appetite. He likes to eat. That makes him the subject of jokes. And those jokes have spurred a backlash from Giants fans and others who point to his on-field performance and say, “Enough. Leave Pablo alone. He’s fine.”

I don’t think it’s fine. Let me tell you why.

Pablo is 5 feet 11 inches tall. When he broke into the majors in 2008, his weight was listed as 240 pounds. That’s the number you’ll find if you look at Pablo’s player page on Baseball-Reference or FanGraphs. By the end of the 2009 season, he was “well north of 250 pounds.” The Giants were concerned enough about his weight, fitness, and overall well-being that they devised Camp Panda, a grueling 6-week training program in the Arizona desert. Pablo’s goal was to get down to 250 pounds.

Whatever benefits Pablo enjoyed from Camp Panda had evaporated toward the end of the 2010 season. By his own admission, Pablo’s weight ballooned to 278 pounds. He was out of shape and it affected his performance on the field. As the Giants marched toward their first World Series Championship since moving to San Francisco, Pablo found himself on the bench more often than not. Juan Uribe moved to third base, Edgar Renteria returned to shortstop and several well-timed home runs later, the Giants were champs.

Back to work for Pablo. He shed 38 pounds before the 2011 season by following a high-protein, low-carb diet and working out regularly. He reported to spring training at 240 pounds, his rookie-year weight. By the 2012 season, however, the extra pounds re-appeared after Pablo broke the hamate bone in his left hand and sat on the disabled list for six weeks. Again, the Giants expressed concern. Then Pablo went out and powered the Giants to their second World Series Championship in three years. What weight problem?

According to Andrew Baggarly of Comcast SportsNet Bay Area, Sandoval’s weight is noted as 242 pounds in the Giants 2013 media guide. Rotoworld lists him at 246 pounds. ESPN and CBSSports have Pablo at 262 pounds. I don’t know his real weight. Neither do you. We do know the Giants are concerned. Again. Manager Bruce Bochy threatened to bench Pablo in the second spring-training game unless he dropped to a certain weight. Pablo met the command and played, although Bochy isn’t quite sure how he did it.

I also don’t know Pablo’s ideal weight. And unless you’re a doctor, fitness trainer, or dietician, you likely don’t know either. Here’s what we do know.

In 2009, at age 22, Pablo hit .330/.357/.586 with 25 home runs. He posted a 146 wRC+ (weighted runs created-plus), a stat that seeks to capture a player’s overall contribution to his team’s run-scoring efforts. Only ten players in the majors posted a higher wRC+ that season. But 2009 was a challenge for Pablo at third base. He posted a -11 Defensive Runs Saved and a -5.4 UZR/150, which means he rated considerably below average for a third baseman. Granted, defensive statistics aren’t nearly as precise as offensive ones, but they give you a sense for Pablo’s play in the field that season.

On the flip side, Pablo’s best season at the hot corner was 2011, when he came into camp at 240 pounds and in the best shape of his career. His DFS jumped to +15 and his UZR/150 reached 17.9. Only Evan Longoria rated higher defensively that season among regular third baseman. It was also Pablo’s best season at the plate, slightly edging out his 2009 campaign. His slash was lower, coming in a .315/.357/.552 but his wRC+ hit 148, good for 15th-best in the majors among players with at least 400 plate appearances. (Pablo missed time with a broken hamate bone in his right hand that season).

Let’s not confuse correlation with causation. We don’t know that a slimmer Pablo led directly to better performance on both sides of the ball. It certainly looks that way, but we don’t know for sure. We do know that better overall fitness leads to greater flexibility, agility and stamina, and that those are needed for optimal performance over the long baseball season.

Folks like to point to Prince Fielder, Tony Gwynn, Dmitri Young and other super-sized players as proof that Pablo’s weight — even in the range of 270 pounds — has not or will not affect his performance. But here’s the catch. None of them played third base. They were either outfielders, first basemen or designated hitters — all much less demanding positions than third base. And even in those demanding positions, most of those players saw their offensive production decline as they approached their 30th birthday. My FanGraphs colleague Jeff Zimmerman recently found that 28.8 years is the average age for peak production from other big-boned players between 5′ 7″ and 6′ 1″.

According to Baseball Reference, here’s the full list of players since 1962 who have (1) played third base, shortstop or second base; (2) are listed at 6′ 2″ or shorter; and (3) are listed at 235 pounds or higher:

Rk Player Ht Wt Age PA H 2B 3B HR BB SO GDP BA OBP SLG
1 Juan Francisco 74 245 22-25 386 93 22 1 14 22 121 8 .258 .303 .440
2 Erick Almonte 74 245 23-33 144 31 7 0 2 8 29 5 .233 .282 .331
3 Juan Uribe 72 240 21-32 5229 1200 252 41 157 294 937 109 .251 .296 .419
4 Pablo Sandoval 71 240 21-25 2311 636 139 14 76 173 300 67 .303 .353 .490

Juan Uribe is the only regular infielder who even comes close to Pablo’s height and weight, and that’s if you peg Sandoval at 240 pounds. Uribe was never the offensive force Pablo can be at the plate; his highest wRC+ was 115 in 2009, at age 30. His career total DRS is 13. That’s two fewer runs than Pablo saved just in the 2011 season. And Uribe has not aged well, at all. The last two seasons with the Dodgers (his age 31 and 32 seasons), he posted a 56 wRC+ and 53 wRC+ and was relegated to the bench.

Pablo is 26 years old. He’ll turn 27 in August. Before last season, he signed a 3-year/$17.15 million contract with the Giants, so he’ll be a free agent after the 2014 season, when he’s 28. As the Giants assess whether to extend Pablo’s contract beyond 2014, they want to see whether he can sustain a healthy diet and a rigorous fitness program. That makes perfect sense. After 28, he may be on the downside of offensive production, if history is any guide. And who knows how long Pablo can sustain an elite glove at third base. History doesn’t help here. There just aren’t enough players in Pablo’s height and weight range who have played third, second, or shortstop. That alone is telling.

The jokes will continue because Pablo is a fun player and seems to take the mostly good-natured ribbing in stride. But his weight is a serious issue for him and for the Giants. As it should be.