football name chain generator, poorly done

import re
import collections

player_re = re.compile(r'^(?P<first>\S+)\s(?P<last>\S+)(?P<hof>\+?)\s(?P<pos>\([A-Z\-,/]*\))\s(?P<years>[\d\-]+)$', re.MULTILINE)

players = collections.defaultdict(list)


class Player(object):
   def __init__(self, first, last, hof='', pos='', years=''):
      self.first = first
      self.last = last
      self.hof = hof
      self.pos = pos
      self.years = years

   def __str__(self):
      return f"{self.first} {self.last}{self.hof} {self.pos} {self.years}"


def load_players():
   global players
   fn = "foosball.txt"
   with open(fn) as pf:
      raw_players = pf.readlines()

   # filter out players who would break regex
   raw_players = [p.strip() for p in raw_players if p.count(' ') == 3]  # First Last (Pos) Years

   for pstr in raw_players:
      pm = player_re.match(pstr)
      if not pm:
         print("Regex failed on {!r}".format(pstr))
         continue
      P = Player(**pm.groupdict())
      players[P.first].append(P)


def print_chain(chain):
   for i, n in enumerate(chain):
      print(f'{i+1:03}. {n}')


def traverse(name, chain):
   if name not in players:
      yield chain
   for p in players[name]:  # todo could sort more greedily
      if p not in chain:
         for res in traverse(p.last, chain + [p]):
            yield res
   yield chain


def main():
   load_players()

   longest_chain = []
   i = 0
   for fn in sorted(players, key=lambda n: len(players[n]), reverse=True):  # start with most common names
      chain = []
      print(i)
      for res in traverse(fn, chain):
         if len(res) > len(longest_chain):
            print("\n{}. new longest chain ({}):".format(i, len(res)))
            print_chain(res)
            longest_chain = res
      i += 1


if __name__ == "__main__":
   main()