Though MLB players don't typically resent their competition, there are several bitter rivalries in the sport today. For personal reasons, certain pairs of guys wouldn't tolerate wearing the same uniform.
Some tried sharing a clubhouse before their irreconcilable differences became too much to overcome. Disdain also develops between individuals who frequently go head to head.
Fans must cherish the following soured relationships. After all, in this era of constant player movement and humongous salaries, we more frequently see mushy alliances formed off the field.
Baseball's juiciest stories involve players who will never get along.
It definitely bothers Brandon McCarthy that he and Logan Morrison have so much in common.
These talented yet injury-prone players were overlooked during the draft process. But several years since debuting in the majors, both have starting jobs.
McCarthy served as a Bleacher Report guest columnist two summers ago and wrote about top MLB Twitter accounts (including his own). He wholeheartedly praised Ozzie Guillen, Derek Holland, Brandon Phillips and others.
His analysis of Morrison's activity, however, wasn't so complimentary.
He confesses "pretty bitter" feelings toward the 25-year-old: "Someone once told me that he was funnier than me on Twitter, so now I kind of hate him...Don't follow Logan Morrison."
These social media moguls have never faced each other during the regular season. That could change in 2013 with the Arizona Diamondbacks and Miami Marlins scheduled to clash six times.
As the "most hated player" in Major League Baseball, A.J. Pierzynski probably has plenty of rivals.
Unfortunately, most are too cowardly to diss him without the protection of anonymity.
Joe Cowley of the Chicago Sun-Times recalls that Boone Logan was one of the rare Pierzynski teammates who found him objectionable.
The lefty reliever was proud of himself for receiving a call-up in 2006 and reportedly rubbed people the wrong way with his "big league ego." His veteran catcher didn't appreciate that and bullied him throughout their three years together.
This anecdote falls in line with comments a National League pitcher directed toward Pierzynski in Men's Journal last summer: "He's been (mean) to guys on his own pitching staff. Basically, if you haven't got five years in the big leagues, he treats you like you're a peasant. He's that kind of guy."
Logan posted an ugly 5.87 ERA and 1.69 WHIP while on the Chicago White Sox, and most of those struggles came with Pierzynski behind the plate.
Manny Ramirez and Kevin Youkilis needed to be separated in the Boston Red Sox dugout in June 2008, according to MLB.com's Ian Browne. At the time, the team downplayed their heated argument, only to trade away Ramirez just eight weeks later.
These past All-Stars approach the game very differently.
Of course, Ramirez is smooth and fun-loving. He rarely over-exerts on the field or shows frustration following a failure. Youkilis, meanwhile, plays with intensity and a chip on his shoulder.
It's been nearly two years since Ramirez set foot on a major league field. Still, his agent tells Jon Paul Morosi of Fox Sports that the 40-year-old wants to continue his career.
The New York Yankees would be asking for a media circus if they gave the Dominican slugger an opportunity.
In 2010, Brandon Phillips and Yadier Molina were at the center of an all-out brawl.
Entering the second game of a midsummer series, the Cincinnati Reds second baseman made fiery comments about the St. Louis Cardinals. He spoke about his deep hatred of the organization and accused his rivals of whining (using slightly stronger language).
Molina definitely didn't appreciate his opponent's accusations.
Phillips instigated the fight in the first inning by smacking his bat against Molina's shin guards. Shouting escalated into a benches-clearing confrontation with violence that we've haven't seen in Major League Baseball since.
MLB.com's Mark Sheldon reports that Molina took exception to Phillips' innocuous yet annoying physical contact: "He's got no friends over here, why are you touching me then? You are not my friend. So don't touch me."
Both men happen to be elite players, though personality-wise, they don't mesh. The 31-year-old Phillips is cocky, extroverted and ostentatious. Molina, on the other hand, is extremely humble.
There will be dozens of more opportunities to see them get at each other's throats, as their contracts run through 2017.
Mark Teixeira would certainly never want to join forces with Vicente Padilla, considering how he has dominated the right-hander in recent years. The New York Yankees first baseman owns a terrific lifetime .333/.526/1.250 batting line in 19 plate appearances against the Nicaragua native.
Teixeira has homered off him in three instances, but been hit by pitches just as many times.
That's no coincidence.
Didier Morais of NESN.com sums up their personal history pretty concisely:
Teixeira has publicly ripped the reliever, claiming Padilla was a headhunter who intentionally threw at hitters. The pair were teammates in Texas in 2006 and 2007, and Teixeira believed he took the brunt of the opposing teams’ retaliation when Padilla plunked batters.
Last season, Padilla poured fuel on the fire by suggesting that Teixeira would be "better off playing a women’s sport" to avoid potential injury.
There unfortunately won't be any new developments in this rivalry for a while, as the veteran reliever resumes his professional career in Japan. Evidently, Teixeira and Padilla can't bear to be in the same hemisphere.