According to real-life references, clubs should have the following regularly ongoing revenue sources:
Gate receipts
Local TV/Radio
Concessions & merchandise
Venue
Advertising & promotions
National
Venue revenue is primarily premium seating (club seats & luxury suites), but also such things as parking and stadium rental for other events. While premium seating could be thought of as a 'modern' category starting with the new parks built in the 1980s and 1990s, the box seats in the parks of old were effectively the premium seating of their day.
National revenue is the income from the league as a whole, and is distributed in equal amounts to each team.
One could argue that advertising & promotions could be combined with concessions & merchandise for OOTP's purposes to streamline revenue sources. But I would argue they should be separate as concessions & merchandise is earned from the fans attending the games, while advertising & promotions can be thought of as the level of corporate support for a club.
To the foregoing can be added revenue that can occur but is not necessarily regularly recurring:
Post-season
Gain on player transactions
Revenue sharing
Luxury tax
Expansion fees
Note that, starting with the 2017 CBA, some of the luxury tax proceeds from paying teams can be distributed to non-paying teams.
On the other side of the ledger, the expenses real-life teams have:
Players (including bonuses and player benefits)
Managers & coaches
Team operations
Venue operations
Scouting
Minor league operations
Administrative & general
Note that real-life sources sometimes roll the costs of the manager and coaches into team operations or as part of player costs. Player benefits include the myriad of in-season benefits the players get such as meal money as well as contributions to the players' pension plan. In 2022 these group benefits cost each team $16 million (plus another $1.67 million per team for the newly created pre-arbitration bonus pool).
Team operations includes such things as travel, hotels, uniforms, insurance, payroll taxes, etc. Venue operations are the cost of operating the team's park, i.e. grounds crew, power, ticket takers, ushers, security, maintenance, etc.
Scouting in real-life sources is sometimes rolled into the player development category, which includes the cost of running the minors. Minor league operations is the cost of running the affiliates which includes the salaries of the players, manager, and coaches, financial support to the affiliate from working agreements, spring training, and so forth. One expense not usually separated out in real-life sources is the cost of signing bonuses to drafted players. Presumably it's included as part of player development.
Expenses which can sometimes occur but are not necessarily regularly recurring:
Loss on player transactions
Revenue sharing
Luxury tax
Real-life example of the 1996–98 Cleveland Indians (which does show signing bonuses for drafted players separately, but on an amortized basis). Percentage of revenue and expense have been added as a convenience to see the proportion each category contributed. The percentage figure for net operating income is that figure divided by the total revenues amount.
Code:
1996 1997 1998
REVENUES
Gate Receipts (net) 45,658 46.0% 49,279 43.8% 55,830 44.0%
Local Media 13,631 13.7% 17,014 15.1% 19,649 15.5%
Concessions & Merchandise (net) 17,717 17.8% 18,562 16.5% 20,353 16.0%
Stadium 7,035 7.1% 8,704 7.7% 9,358 7.4%
Advertising & Promotions (net) 4,046 4.1% 5,031 4.5% 6,171 4.9%
National (net) 11,225 11.3% 13,932 12.4% 15,600 12.3%
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Total revenues 99,312 100.0% 112,522 100.0% 126,961 100.0%
OPERATING EXPENSES
Players 47,687 56.0% 58,865 58.7% 56,843 52.8%
Major league team 5,768 6.8% 5,155 5.1% 9,769 9.1%
Player development 8,889 10.4% 10,536 10.5% 11,540 10.7%
Ballpark operations 10,834 12.7% 11,539 11.5% 12,283 11.4%
Administrative and general 8,756 10.3% 10,499 10.5% 12,709 11.8%
Signing bonuses and contracts 3,212 3.8% 3,630 3.6% 4,412 4.1%
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Total operating expenses 85,146 100.0% 100,224 100.0% 107,556 100.0%
OPERATING INCOME (LOSS) 14,166 14.3% 12,298 10.9% 19,405 15.3%
SPECIAL INCOME (EXPENSE)
Post-season (net) 624 6,799 5,374
Player transactions (net) 616 2,696 (1,355)
Revenue sharing (5,731) (7,186) (10,209)
Luxury tax 0 (2,065) (24)
Expansion fees 0 9,286 0
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Total special income (4,491) 9,530 (6,214)
NET OPERATING INCOME (LOSS) 9,675 9.7% 21,828 19.4% 13,191 10.4%