In baseball, transactions can be many things. Some border on the banal. Others are more momentous: a fading star declares retirement, a blockbuster trade becomes official, a high-priced free agent or draft pick signs with his new team. When one of the latter deals goes down, baseball writers spring into action, devoting ink and pixels alike to analyses of its principal players and ramifications. In a very real sense, transactions make the baseball world go ’round, ebbing and flowing like a circulatory system of athletic talent.

Rather than focus on any one signing or swap, let’s pull back our perspective and take a look at the sum of the sport’s transactions. Retrosheet, the baseball analysis gift that never stops giving, publishes an annually updated downloadable database of player movements from 1873 onwards, broken down by transaction type. With a little coaxing in Excel, we can use this data to construct a visual record of each and every move made over the course of a season. I may be stretching a metaphor that wasn’t the strongest to begin with, but if transactions are baseball’s circulatory system, this is its EKG:


If you want proof of the contention that modern baseball has no offseason, look no further: that profusion of blue through the cold winter months hints at plenty of fuel for the hot stove. According to Retrosheet’s data, only 17 of the 365 days in the year were devoid of transactions in both 2008 and 2009. For the purposes of this graph, I excluded all transactions that Retrosheet designated as “Fg,” or “Free agent granted.” As you’ll soon see, “Fg” transactions are concentrated in a brief span of time, and come fast and furious within that period, so to include them here would distort the display.

Each spike appearing on the graph has an identifiable origin, imparting a pleasing sense of order to the image. The jump in activity around the first of April marks the final round of spring training cuts, when teams grant releases to their last batches of disappointed major-league hopefuls. The spike around July 31 denotes the non-waiver trading deadline and the subsequent round of releases granted to make room for new acquisitions, followed by a small aftershock around the waiver trading deadline a month later. A flurry of free-agent signings follow the opening of free-agent-hunting season in late November, and another spate of trades and signings accompany the Winter Meetings, which begin at the close of the first week of December. Even hard-working front-office types more or less take a break for the week of Christmas and New Year’s, but the action returns in earnest once the calendar flips over.

Retrosheet’s database also allows us to filter by transaction type in order to take a more granular look at MLB activity. For example, here’s a display showing only trades:


We see that the trade market peaks around the non-waiver deadline, hits lesser heights around the waiver deadline and Winter Meetings, and otherwise remains mostly dormant for most of the year, with isolated deals consummated at irregular intervals. How about free-agent signings?


Free-agent signing never ceases entirely, thought it nearly comes to a standstill between the conclusion of the regular season and the day when the current year’s mercenary class makes its intentions to file for free agency clear. However, the offseason is the free-agent market’s time to shine, with activity at its height from late November through late January, excluding a brief recess for the holidays (yes, folks, even Scott Boras has a family).

Baseball transactions are fun for observers, but they do have a dark side. Had Isaac Newton been a general manager, he likely would have noted that once a roster is full, each addition to a 40-man roster requires an equal and opposite subtraction; the law of conservation of roster spots states that spots on the 40-man can neither be created nor lost, only transformed from Dan Haren into Joe Saunders. Here’s a visual timeline of when fringe major leaguers tend to lose their jobs:


As noted earlier, major-league teams rain releases when rosters are finalized at the end of spring training, as fun in the sun gives way to at least a temporary period of unemployment for a number of players deemed unworthy of major-league roster spots. After that, releases come sporadically, with clusters grouped close to the trading deadlines, as new arrivals displace unwanted incumbents.

And finally, the reason why I excluded transactions designated as “Fg”:


The 15-day free-agent filing period begins the day after the World Series, and the majority of eligible players declare their receptiveness to the idea of being wooed immediately after its conclusion. The deciding Game 6 of the 2009 World Series fell on November 4, touching off a filing frenzy the following day.

One class of transaction mostly missing from the graphs above consists of amateur draft picks. Players aren’t assigned Retrosheet IDs until after the seasons in which they make their MLB debuts; although they may not realize it, the ceremonial bestowing of a RetroID is every bit the sign that a rookie has arrived as is the first handout of major-league meal money, or the proverbial appearance in The Baseball Encyclopedia. Because players without RetroIDs don’t show up in the database, recent draftees who haven’t yet made it to the majors are conspicuously absent from the 2008-2009 data. If we venture back a decade to the year 2000, those amateur draftees make their presence felt. In fact, if we include draft selections, all other days pale in comparison to June 5 in terms of transactions:


Let’s turn the clock back another couple decades to when the Empire was striking back at box offices. Here’s the transaction picture from 1980:


In addition to the amateur draft spike in early June, we see another sizeable spike on January 11. We can chalk that one up to amateur draftees, too: until 1986, a separate draft was held in January for high school and college players who graduated over the winter. Let’s remove those pesky amateur draftees and take another look:


This view doesn’t look so unfamiliar, though a couple of elements set it apart from our graphical look at the present day. For one thing, in 1980, the trading deadline was still set at June 15, and doesn’t appear to have generated much action. The date was pushed back before long to allow GMs more time to decide whether they were buyers or sellers; this graph serves as evidence of why that change was made. Secondly, check out that spike at Winter Meeting time—perhaps those tales of wild Winter Meetings past told by baseball lifers aren’t all hot air.

Before we conclude, follow me one step further back to the year when the underrated “Junior’s Farm” peaked at No. 10 on the charts. This time we’ll omit amateur draftees from the get-go:


The most immediately obvious aspect of 1975’s transactions is that there were so few of them, in relation to the years we looked at earlier. Assuming that Retrosheet’s records are complete, 1975 saw only 305 transactions, compared to 552 in 1980 and no fewer than 1,190 in 2009. If Christina Kahrl had been analyzing transactions at the dawn of the disco era, she would have found herself with a considerable amount of free time in which to strap on her roller skates. In 1975, six of the teams we’re familiar with today had yet to be born; fewer teams meant fewer transactions. However, much of the dearth of transactions can be explained by the reserve clause, which bound players indefinitely to a single team. While the reserve clause reigned, free agency, such as it was, looked something like this:


Compare that to the third graph displayed in this article; these lines are tiny enough to give Marvin Miller flashback-filled nightmares, while bringing tears to the eyes of many a nostalgic ex-owner. This state of affairs wouldn’t last much longer; the Seitz decision that abolished the reserve clause was rendered in late December of ’75, granting players greater freedom of movement, and, decades down the road, giving Christina significantly more moves about which to write.