The news is a few days old now, but ESPN's Adam Rubin reported that Major League Baseball has told all thirty teams that they must medal detectors in place by 2015. Upon arrival, fans will be required to either pass through a stand-alone medal detector or be wanded by a security guard. This practice was implemented at the All-Star Game last season, so it will not be the first time some of you have experienced when it arrives for good.
This upgraded security is a direct result of the threats park patrons face when they go to any major sporting event these days, to include direct assaults from other fans or even terrorism. Major events such as the All-Star Game last summer or the Superbowl next weekend now require present major security concerns serious enough to involve the Department of Homeland Security. The average fan won't mind, but there are always those few (think about the unruly guy in the TSA line at the airport) who take offense to any new security practice.
I think its worth noting that the average fan is much more likely to have their ballpark experience ruined and/or be harmed by a drunk fan. While I respect that Major League Baseball hopes to accomplish by implementing these measures, if they were concerned about the average fan on a daily basis they would find a way to clamp down on patrons over imbibing. I enjoy an adult beverage and have on occasion strapped on a good buzz at the ballpark, but some fans can't handle it.
Nonetheless, fans should be prepared for longer lines at the gates when these screenings begin. In effect that will be the worst to come of this. However, threats to your safety at the game are real and Major League Baseball is correct to force fans through this process, whether they like it or not.